ADRF6755ACPZ-R7 [ADI]

100 MHz to 2400 MHz I/Q Modulator with Integrated Fractional-N PLL and VCO;
ADRF6755ACPZ-R7
型号: ADRF6755ACPZ-R7
厂家: ADI    ADI
描述:

100 MHz to 2400 MHz I/Q Modulator with Integrated Fractional-N PLL and VCO

文件: 总48页 (文件大小:2098K)
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100 MHz to 2400 MHz I/Q Modulator  
with Integrated Fractional-N PLL and VCO  
Data Sheet  
ADRF6755  
FEATURES  
GENERAL DESCRIPTION  
I/Q modulator with integrated fractional-N PLL and VCO  
Gain control span: 47 dB in 1 dB steps  
The ADRF6755 is a highly integrated quadrature modulator,  
frequency synthesizer, and programmable attenuator. The device  
covers an operating frequency range from 100 MHz to 2400 MHz  
for use in satellite, cellular, and broadband communications.  
Output frequency range: 100 MHz to 2400 MHz  
Output 1 dB compression: 8 dBm at LO = 1800 MHz  
Output IP3: 20.5 dBm at LO = 1800 MHz  
Noise floor: −161 dBm/Hz at LO = 1800 MHz  
Baseband modulation bandwidth: 600 MHz (3 dB)  
Output frequency resolution: 1 Hz  
The ADRF6755 modulator includes a high modulus, fractional-N  
frequency synthesizer with integrated VCO, providing less than  
1 Hz frequency resolution, and a 47 dB digitally controlled output  
attenuator with 1 dB steps.  
SPI and I2C-compatible serial interfaces  
Power supply: 5 V/380 mA  
Control of all the on-chip registers is through a user-selected SPI  
interface or I2C interface. The device operates from a single power  
supply ranging from 4.75 V to 5.25 V.  
VCC1  
VCC2  
VCC3  
VCC4  
LOMON  
LOMON  
3.3V  
REGULATOR  
REGOUT  
IBB  
IBB  
VREG1  
VREG2  
VREG3  
VREG4  
VREG5  
VREG6  
CCOMP1  
CCOMP2  
CCOMP3  
47dB  
GAINCONTROL  
RANGE  
RFDIVIDER  
0°/90°  
RFOUT  
VCO  
CORE  
VTUNE  
TXDIS  
QBB  
QBB  
RSET  
REFERENCE  
×2  
5-BIT  
DIVIDER  
REFIN  
REFIN  
÷2  
+
PHASE  
DOUBLER  
CHARGE  
PUMP  
FREQUENCY  
DETECTOR  
CP  
NC  
CURRENT SETTING  
CR9[7:4]  
N-COUNTER  
NC  
THIRD-ORDER  
FRACTIONAL  
INTERPOLATOR  
LDET  
SDI/SDA  
CLK/SCL  
SDO  
2
SPI/I C  
INTERFACE  
CS  
FRACTIONAL  
REGISTER  
MODULUS  
INTEGER  
REGISTER  
25  
2
ADRF6755  
AGND  
DGND  
Figure 1.  
Rev. B  
Document Feedback  
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responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other  
rightsof third parties that may result fromits use. Specifications subject to change without notice. No  
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.  
Trademarks andregisteredtrademarks are the property of their respective owners.  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781.329.4700 ©2012–2013 Analog Devices, Inc. All rights reserved.  
Technical Support  
www.analog.com  
 
 
ADRF6755  
Data Sheet  
TABLE OF CONTENTS  
Features .............................................................................................. 1  
SPI Interface................................................................................ 27  
Program Modes .......................................................................... 29  
Register Map ................................................................................... 31  
Register Map Summary ............................................................. 31  
Register Bit Descriptions........................................................... 32  
Suggested Power-Up Sequence..................................................... 35  
Initial Register Write Sequence ................................................ 35  
Evaluation Board ............................................................................ 37  
General Description................................................................... 37  
Hardware Description ............................................................... 37  
PCB Artwork............................................................................... 41  
Bill of Materials........................................................................... 44  
Outline Dimensions....................................................................... 45  
Ordering Guide .......................................................................... 45  
General Description ......................................................................... 1  
Revision History ............................................................................... 2  
Specifications..................................................................................... 3  
Timing Characteristics ................................................................ 8  
Absolute Maximum Ratings.......................................................... 10  
ESD Caution................................................................................ 10  
Pin Configuration and Function Descriptions........................... 11  
Typical Performance Characteristics ........................................... 13  
Theory of Operation ...................................................................... 21  
Overview...................................................................................... 21  
PLL Synthesizer and VCO......................................................... 21  
Quadrature Modulator .............................................................. 24  
Attenuator.................................................................................... 25  
Voltage Regulator ....................................................................... 25  
I2C Interface ................................................................................ 25  
REVISION HISTORY  
4/13—Rev. A to Rev. B  
Changes to Ordering Guide .......................................................... 45  
11/12—Rev. 0 to Rev. A  
Changes to Figure 1.......................................................................... 1  
Changes to Input Frequency Parameter, Table 1.......................... 6  
Changes to Bit 7 Description, Table 27 and Bit 6 Description,  
Table 27 ............................................................................................ 34  
Changed 0x00 to 0x60 in Step 13 ................................................. 35  
Updated Outline Dimensions....................................................... 45  
Changes to Ordering Guide .......................................................... 45  
7/12—Revision 0: Initial Version  
Rev. B | Page 2 of 48  
 
Data Sheet  
ADRF6755  
SPECIFICATIONS  
VCC = 5 V 5%, operating temperature range = −40°C to +85°C, I/Q inputs = 0.9 V p-p differential sine waves in quadrature on a 500 mV dc  
bias, REFIN = 80 MHz, PFD = 40 MHz, baseband frequency = 1 MHz, LOMON off, loop bandwidth (LBW) = 100 kHz, ICP = 5 mA, unless  
otherwise noted.  
Table 1.  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
OPERATING FREQUENCY RANGE  
RF OUTPUT = 100 MHz  
Nominal Output Power  
Gain Flatness  
100  
2400  
MHz  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
−0.2  
2.0  
dBm  
dB  
Output P1dB  
9.0  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
21.0  
−12  
−55  
−80  
−70  
−153  
−60  
−85  
dBm  
dB  
dBc  
dBm  
dBc  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
−90  
Phase Noise  
−106  
−116  
−127  
−131  
−146  
−152  
0.02  
Integrated Phase Noise  
RF OUTPUT = 300 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
0.2  
0.5  
dBm  
dB  
Output P1dB  
9.3  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
23.0  
−20  
−50  
−75  
−70  
−158  
−60  
−85  
−85  
−105  
−113  
−117  
−122  
−145  
−150  
0.04  
dBm  
dB  
dBc  
dBm  
dBc  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
Integrated Phase Noise  
Rev. B | Page 3 of 48  
 
 
ADRF6755  
Data Sheet  
Parameter  
Test Conditions/Comments  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
Min  
Typ  
Max  
Unit  
RF OUTPUT = 700 MHz  
Nominal Output Power  
Gain Flatness  
0.2  
0.5  
dBm  
dB  
Output P1dB  
9.4  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
23.0  
−16  
−48  
−70  
−70  
−158  
−60  
−60  
−85  
−97  
−106  
−112  
−115  
−139  
−154  
0.07  
dBm  
dB  
dBc  
dBm  
dBc  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
Integrated Phase Noise  
RF OUTPUT = 900 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
0.0  
0.5  
dBm  
dB  
Output P1dB  
9.2  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
22.8  
−15  
−48  
−68  
−60  
−158.5  
−152  
−171  
−60  
−60  
−80  
dBm  
dB  
dBc  
dBm  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
dBc  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Attenuator setting = 0 dB to 21 dB, carrier offset = 10 MHz  
Attenuator setting = 21 dB to 47 dB, carrier offset = 10 MHz  
dBm/Hz  
dBc/Hz  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
−94  
−104  
−109  
−114  
−139  
−154  
0.11  
Integrated Phase Noise  
RF OUTPUT = 1800 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
−0.4  
0.5  
dBm  
dB  
Output P1dB  
Output IP3  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
8.0  
dBm  
dBm  
dB  
dBc  
dBm  
dBc  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
20.5  
−13  
−45  
−53  
−45  
Rev. B | Page 4 of 48  
Data Sheet  
ADRF6755  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
Noise Floor  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Attenuator setting = 0 dB to 21 dB, carrier offset = 10 MHz  
Attenuator setting = 21 dB to 47 dB, carrier offset = 10 MHz  
−161  
−150  
−170  
−58  
−60  
−75  
dBm/Hz  
dBc/Hz  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
−89  
−99  
−103  
−108  
−133  
−152  
0.17  
Integrated Phase Noise  
RF OUTPUT = 1875 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
−0.6  
0.5  
dBm  
dB  
Output P1dB  
7.8  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
20.2  
−13  
−45  
−52  
−50  
−160  
−150  
−170  
−60  
−60  
−73  
−89  
−97  
−103  
−108  
−133  
−152  
0.18  
dBm  
dB  
dBc  
dBm  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
dBc  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Attenuator setting = 0 dB to 21 dB, carrier offset = 10 MHz  
Attenuator setting = 21 dB to 47 dB, carrier offset = 10 MHz  
dBm/Hz  
dBc/Hz  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
Integrated Phase Noise  
RF OUTPUT = 2100 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
−1.0  
0.5  
dBm  
dB  
Output P1dB  
Output IP3  
7.4  
dBm  
dBm  
dB  
dBc  
dBm  
dBc  
dBm/Hz  
dBc/Hz  
dBm/Hz  
dBc  
dBc  
dBc  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
19.5  
−12  
−44  
−51  
−45  
−161  
−149  
−170  
−60  
−60  
−67  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Attenuator setting = 0 dB to 21 dB, carrier offset = 10 MHz  
Attenuator setting = 21 dB to 47 dB, carrier offset = 10 MHz  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
Rev. B | Page 5 of 48  
ADRF6755  
Data Sheet  
Parameter  
Test Conditions/Comments  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Min  
Typ  
Max  
Unit  
Phase Noise  
−88  
−98  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
−101  
−108  
−134  
−152  
0.25  
Integrated Phase Noise  
RF OUTPUT = 2400 MHz  
Nominal Output Power  
Gain Flatness  
RFOUT pin  
VIQ = 0.9 V p-p differential  
Any 40 MHz  
−1.7  
0.5  
dBm  
dB  
Output P1dB  
6.5  
dBm  
Output IP3  
f1BB = 3.5 MHz, f2BB = 4.5 MHz, POUT = −6 dBm per tone  
Attenuator setting = 0 dB  
Attenuator setting = 0 dB to 47 dB  
Attenuator setting = 0 dB to 47 dB  
18.5  
−11  
−43  
−60  
−40  
−160.5  
−148  
−170  
−55  
−55  
−64  
dBm  
dB  
dBc  
dBm  
Output Return Loss  
LO Carrier Feedthrough1  
2× LO Carrier Feedthrough  
Sideband Suppression  
Noise Floor  
dBc  
I/Q inputs = 0 V p-p differential, attenuator setting = 0 dB  
Attenuator setting = 0 dB to 21 dB, carrier offset = 10 MHz  
Attenuator setting = 21 dB to 47 dB, carrier offset = 10 MHz  
dBm/Hz  
dBc/Hz  
dBm/Hz  
dBc  
dBc  
dBc  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
dBc/Hz  
° rms  
Baseband Harmonics  
Synthesizer Spurs  
Integer boundary < loop bandwidth  
>10 MHz offset from carrier  
100 Hz offset  
1 kHz offset  
10 kHz offset  
100 kHz offset  
1 MHz offset  
10 MHz offset  
1 kHz to 8 MHz integration bandwidth  
Phase Noise  
−85  
−96  
−100  
−107  
−132  
−152  
0.25  
Integrated Phase Noise  
REFERENCE CHARACTERISTICS  
Input Frequency  
REFIN pin  
With reference divide-by-2 enabled  
With reference divide-by-2 disabled  
With reference doubler enabled  
AC-coupled  
10  
10  
10  
0.4  
300  
165  
80  
VREG  
10  
MHz  
MHz  
MHz  
V p-p  
pF  
Input Sensitivity  
Input Capacitance  
Input Current  
CHARGE PUMP  
ICP Sink/Source  
High Value  
Low Value  
Absolute Accuracy  
VCO  
100  
µA  
Programmable, RSET = 4.7 kΩ  
5
mA  
µA  
%
312.5  
4.0  
Gain  
KVCO  
25  
MHz/V  
SYNTHESIZER  
Frequency Resolution  
Frequency Settling  
Maximum Frequency Step for  
No Autocalibration  
LO = 100 MHz to 2400 MHz  
1
Hz  
ms  
Any step size, maximum frequency error = 100 Hz  
Frequency step with no autocalibration routine;  
Register CR24, Bit 0 = 1  
0.17  
100/2RFDIV kHz  
Phase Detector Frequency  
10  
40  
MHz  
Rev. B | Page 6 of 48  
Data Sheet  
ADRF6755  
Parameter  
Test Conditions/Comments  
Min  
Typ  
Max  
Unit  
GAIN CONTROL  
Gain Range  
Step Size  
47  
1
0.3  
dB  
dB  
dB  
Relative Step Accuracy  
Fixed frequency, adjacent steps, all attenuation steps,  
LO > 300 MHz2  
Over full frequency range, adjacent steps, all attenuation  
1.5  
dB  
steps, LO > 300 MHz3  
Absolute Step Accuracy4  
Output Settling Time  
OUTPUT DISABLE  
47 dB attenuation step, LO > 300 MHz5  
Any step; output power settled to 0.2 dB  
TXDIS pin  
−2.0  
15  
dB  
µs  
Off Isolation  
RFOUT, attenuator setting = 0 dB to 47 dB, TXDIS high  
LO, attenuator setting = 0 dB to 47 dB, TXDIS high  
2× LO, attenuator setting = 0 dB to 47 dB, TXDIS high  
TXDIS high to low: output power to 90% of envelope  
Frequency settling to 100 Hz  
−100  
−75  
−50  
180  
20  
dBm  
dBm  
dBm  
ns  
Turn-On Settling Time  
µs  
Turn-Off Settling Time  
MONITOR OUTPUT  
TXDIS low to high (to −55 dBm)  
350  
ns  
LOMON, LOMON pins  
Nominal Output Power  
BASEBAND INPUTS  
−24  
dBm  
IBB, IBB, QBB, QBB pins  
I and Q Input Bias Level  
3 dB Bandwidth  
500  
600  
mV  
MHz  
LOGIC INPUTS  
Input High Voltage, VINH  
Input Low Voltage, VINL  
Input High Voltage, VINH  
Input Low Voltage, VINL  
Input Current, IINH/IINL  
Input Capacitance, CIN  
LOGIC OUTPUTS  
CS, TXDIS pins  
CS, TXDIS pins  
SDI/SDA, CLK/SCL pins  
SDI/SDA, CLK/SCL pins  
CS, TXDIS, SDI/SDA, CLK/SCL pins  
CS, TXDIS, SDI/SDA, CLK/SCL pins  
1.4  
2.1  
V
V
V
V
µA  
pF  
0.6  
1.1  
1
10  
Output High Voltage, VOH  
Output Low Voltage, VOL  
SDO, LDET pins; IOH = 500 μA  
SDO, LDET pins; IOL = 500 μA  
SDA (SDI/SDA); IOL = 3 mA  
2.8  
V
V
V
0.4  
0.4  
POWER SUPPLIES  
VCC1, VCC2, VCC3, VCC4, VREG1, VREG2, VREG3, VREG4,  
VREG5, VREG6, and REGOUT pins;  
REGOUT normally connected to VREG1, VREG2, VREG3,  
VREG4, VREG5, and VREG6  
Voltage Range  
VCC1, VCC2, VCC3, and VCC4  
REGOUT, VREG1, VREG2, VREG3, VREG4, VREG5, and  
VREG6  
VCC1, VCC2, VCC3, and VCC4 combined; REGOUT con-  
nected to VREG1, VREG2, VREG3, VREG4, VREG5, and  
VREG6  
CR29[0] = 0, power down modulator,  
CR12[2] = 1, power down PLL,  
4.75  
5
3.3  
5.25  
420  
V
V
Supply Current  
380  
7
mA  
mA  
Power-Down Current  
CR28[4] = 1, power down RFDIVIDER,  
CR27[2] = 0, power down LOMON  
Operating Temperature  
−40  
+85  
°C  
1 LO carrier feedthrough is expressed in dBc relative to the RF output power changing as the attenuator is stepped. LO carrier feedthrough is constant as the RF output  
is altered due to a change in the I/Q input amplitude.  
2 For relative step accuracy at LO < 300 MHz, refer to Figure 37.  
3 For relative step accuracy over frequency range at LO < 300 MHz, refer to Figure 39.  
4 All other attenuation steps have an absolute error of < 2.0 dB.  
5 For absolute step accuracy at LO < 300 MHz, refer to Figure 40.  
Rev. B | Page 7 of 48  
 
ADRF6755  
Data Sheet  
TIMING CHARACTERISTICS  
I2C Interface Timing  
Table 2.  
Parameter1  
Symbol  
fSCL  
tHIGH  
Limit  
400  
600  
1300  
600  
600  
100  
300  
600  
900  
900  
1300  
Unit  
SCL Clock Frequency  
SCL Pulse Width High  
SCL Pulse Width Low  
Start Condition Hold Time  
Start Condition Setup Time  
Data Setup Time  
Data Hold Time  
Stop Condition Setup Time  
Data Valid Time  
kHz max  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns max  
ns max  
ns min  
tLOW  
tHD;STA  
tSU;STA  
tSU;DAT  
tHD;DAT  
tSU;STO  
tVD;DAT  
tVD;ACK  
tBUF  
Data Valid Acknowledge Time  
Bus Free Time  
1 See Figure 2.  
tVD;DAT AND  
tVD;ACK (ACK SIGNAL ONLY)  
tSU;DAT  
tBUF  
SDA  
tSU;STA  
tSU;STO  
tHD;STA  
tLOW  
SCL  
S
S
P
S
1/fSCL  
tHD;DAT  
tHIGH  
START  
CONDITION  
STOP  
CONDITION  
Figure 2. I2C Port Timing Diagram  
Rev. B | Page 8 of 48  
 
 
 
Data Sheet  
ADRF6755  
SPI Interface Timing  
Table 3.  
Parameter1  
Symbol  
Limit  
20  
15  
15  
5
10  
5
5
Unit  
CLK Frequency  
fCLK  
t1  
t2  
t3  
t4  
t5  
t6  
t7  
t8  
MHz max  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns min  
ns max  
CLK Pulse Width High  
CLK Pulse Width Low  
Start Condition Hold Time  
Data Setup Time  
Data Hold Time  
Stop Condition Setup Time  
SDO Access Time  
15  
25  
CS to SDO High Impedance  
1 See Figure 3.  
t3  
CS  
t1  
CLK  
SDI  
t6  
t2  
t4  
t5  
SDO  
t7  
t8  
Figure 3. SPI Port Timing Diagram  
Rev. B | Page 9 of 48  
 
 
 
 
 
ADRF6755  
Data Sheet  
ABSOLUTE MAXIMUM RATINGS  
Table 4.  
Parameter  
Stresses above those listed under Absolute Maximum Ratings  
may cause permanent damage to the device. This is a stress  
rating only; functional operation of the device at these or any  
other conditions above those indicated in the operational  
section of this specification is not implied. Exposure to absolute  
maximum rating conditions for extended periods may affect  
device reliability.  
Rating  
VCC1, VCC2, VCC3, and VCC4 Supply Voltage −0.3 V to +6 V  
VREG1, VREG2, VREG3, VREG4, VREG5, and  
VREG6 Supply Voltage  
−0.3 V to +4 V  
IBB, IBB, QBB, and QBB  
0 V to 2.5 V  
Digital I/O  
−0.3 V to +4 V  
−0.3 V to +4 V  
Analog I/O (Other Than IBB, IBB, QBB, and  
QBB)  
ESD CAUTION  
Maximum Junction Temperature  
Storage Temperature Range  
125°C  
−65°C to +150°C  
Rev. B | Page 10 of 48  
 
 
Data Sheet  
ADRF6755  
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS  
VCC4  
IBB  
1
2
3
4
5
6
7
8
9
PIN 1  
INDICATOR  
42 VCC3  
41 VCC3  
IBB  
40 AGND  
QBB  
QBB  
AGND  
RSET  
NC  
CP  
NC 10  
VCC1 11  
39 AGND  
38 VTUNE  
37 AGND  
ADRF6755  
36 VREG6  
35 CCOMP3  
34 CCOMP2  
33 CCOMP1  
32 DGND  
TOP VIEW  
(Not to Scale)  
REGOUT 12  
VREG1 13  
VREG2 14  
31 VREG5  
30 CLK/SCL  
29 SDI/SDA  
NOTES  
1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN.  
2. CONNECT EXPOSED PAD TO GROUND PLANE VIA  
A LOW IMPEDANCE PATH.  
Figure 4. Pin Configuration  
Table 5. Pin Function Descriptions  
Pin No. Mnemonic  
11, 55, 56, 41, 42, 1 VCC1 to VCC4  
Description  
Positive Power Supplies for I/Q Modulator. Apply a 5 V power supply to VCC1, which should be  
decoupled with power supply decoupling capacitors. Connect VCC2, VCC3, and VCC4 to the same  
5 V power supply.  
12  
REGOUT  
3.3 V Output Supply. Drives VREG1, VREG2, VREG3, VREG4, VREG5, and VREG6.  
13, 14, 15, 16, 31,  
36  
VREG1 to  
VREG6  
Positive Power Supplies for PLL Synthesizer, VCO, and Serial Port. Connect these pins to REGOUT  
(3.3 V) and decouple them separately.  
6, 19, 20, 21, 22, 23, AGND  
24, 37, 39, 40, 46, 47,  
Analog Ground. Connect to a low impedance ground plane.  
49, 50, 51, 52, 53, 54  
32  
DGND  
Digital Ground. Connect to the same low impedance ground plane as the AGND pins.  
2, 3  
IBB, IBB  
Differential In-Phase Baseband Inputs. These high impedance inputs must be dc biased to approx-  
imately 500 mV dc and should be driven from a low impedance source. Nominal characterized ac signal  
swing is 450 mV p-p on each pin. These inputs are not self-biased and must be externally biased.  
4, 5  
QBB, QBB  
Differential Quadrature Baseband Inputs. These high impedance inputs must be dc-biased to  
approximately 500 mV dc and should be driven from a low impedance source. Nominal charac-  
terized ac signal swing is 450 mV p-p on each pin. These inputs are not self-biased and must be  
externally biased.  
33, 34, 35  
CCOMP1 to  
CCOMP3  
Internal Compensation Nodes. These pins must be decoupled to ground with a 100 nF capacitor.  
38  
7
VTUNE  
Control Input to the VCO. This voltage determines the output frequency and is derived from  
filtering the CP output voltage.  
Charge Pump Current Set. Connecting a resistor between this pin and ground sets the maximum  
charge pump output current. The relationship between ICP and RSET is as follows:  
RSET  
23.5  
ICPmax  
=
RSET  
where RSET = 4.7 kΩ and ICP max = 5 mA.  
9
CP  
CS  
Charge Pump Output. When enabled, this output provides ICP to the external loop filter, which, in  
turn, drives the internal VCO.  
Chip Select, CMOS Input. When CS is high, the data stored in the shift registers is loaded into one of  
31 latches. In I2C mode, when CS is high, the slave address of the device is 0x60, and, when CS is  
low, the slave address is 0x40.  
27  
Rev. B | Page 11 of 48  
 
ADRF6755  
Data Sheet  
Pin No.  
Mnemonic  
Description  
29  
SDI/SDA  
Serial Data Input for SPI Port/Serial Data Input/Output for I2C Port. In SPI mode, this pin is a high  
impedance CMOS data input, and data is loaded in an 8-bit word. In I2C mode, this pin is a bidirec-  
tional port.  
30  
CLK/SCL  
Serial Clock Input for SPI/I2C Port. This serial clock is used to clock in the serial data to the registers.  
This input is a high impedance CMOS input.  
28  
17  
18  
48  
45  
SDO  
Serial Data Output for SPI Port. Register states can be read back on the SDO data output line.  
Reference Input. This high impedance CMOS input should be ac-coupled.  
Reference Input Bar. This pin should be either grounded or ac-coupled to ground.  
RF Output. Single-ended, 50 Ω, internally biased RF output. This pin must be ac-coupled to the load.  
Output Disable. This pin can be used to disable the RF output. Connect to a high logic level to  
disable the output. Connect to a low logic level for normal operation.  
REFIN  
REFIN  
RFOUT  
TXDIS  
25, 26  
LOMON,  
LOMON  
Differential Monitor Outputs. These pins provide a replica of the internal local oscillator frequency  
(1× LO) at four different power levels: −6 dBm, −12 dBm, −18 dBm, and −24 dBm, approximately.  
These open-collector outputs must be terminated with external resistors to REGOUT. These outputs  
can be disabled through serial port programming and should be tied to REGOUT if not used.  
8, 10  
44  
NC  
LDET  
No Connect. Do not connect to these pins.  
Lock Detect. This output pin indicates the state of the PLL: a high level indicates a locked condition,  
whereas a low level indicates a loss of lock condition.  
43  
MUXOUT  
EP  
Mux Output. This pin is a test output for diagnostic use only. Do not connect to this pin.  
Exposed Paddle. Connect to ground plane via a low impedance path.  
Exposed Paddle  
Rev. B | Page 12 of 48  
Data Sheet  
ADRF6755  
TYPICAL PERFORMANCE CHARACTERISTICS  
VCC = 5 V 5%, operating temperature range = −40°C to +85°C, I/Q inputs = 0.9 V p-p differential sine waves in quadrature on a 500 mV dc  
bias, REFIN = 80 MHz, PFD = 40 MHz, baseband frequency = 1 MHz, LOMON is off, loop bandwidth (LBW) = 100 kHz, ICP = 5 mA,  
unless otherwise noted. A nominal condition is defined as 25°C, 5.00 V, and an LO frequency of 1800 MHz. A worst-case condition is  
defined as having the worst-case temperature, supply voltage, and LO frequency.  
2
60  
50  
40  
30  
20  
10  
0
NOMINAL  
WORST CASE  
1
0
–1  
–2  
–3  
–4  
–5  
25°C; 5V  
85°C; 4.75V  
85°C; 5.25V  
–40°C; 4.75V  
–40°C; 5.25V  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
–60  
–55  
–50  
–45  
–40  
–35  
–30  
LO FREQUENCY (MHz)  
SIDEBAND SUPPRESSION (dBc)  
Figure 5. Output Power vs. LO Frequency, Supply, and Temperature  
Figure 8. Sideband Suppression Distribution at Nominal and  
Worst-Case Conditions  
–30  
25  
NOMINAL  
WORST CASE  
–35  
–40  
–45  
–50  
–55  
–60  
–65  
–70  
–75  
–80  
20  
15  
10  
5
0
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
–4.2 –3.8 –3.4 –3.0 –2.6 –2.2 –1.8 –1.4 –1.0 –0.6 –0.2 0.2 0.6 1.0  
LO FREQUENCY (MHz)  
OUTPUT POWER (dBm)  
Figure 9. LO Carrier Feedthrough vs. LO Frequency, Attenuation,  
Supply, and Temperature  
Figure 6. Output Power Distribution at Nominal and  
Worst-Case Conditions  
80  
0
NOMINAL  
+25°C, 5.00V  
WORST CASE  
70  
+85°C, 4.75V  
–10  
+85°C, 5.25V  
–40°C, 4.75V  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–40°C, 5.25V  
60  
50  
40  
30  
20  
10  
0
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
–60 –58 –56 –54 –52 –50 –48 –46 –44 –42 –40 –38 –36 –34 –32 –30  
LO CARRIER FEEDTHROUGH (dBc)  
LO FREQUENCY (MHz)  
Figure 7. Sideband Suppression vs. LO Frequency, Supply, and Temperature  
Figure 10. LO Carrier Feedthrough Distribution at Nominal and Worst-Case  
Conditions and Attenuation Setting  
Rev. B | Page 13 of 48  
 
ADRF6755  
Data Sheet  
–40  
45  
40  
35  
30  
25  
20  
15  
10  
5
NOMINAL  
WORST CASE  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
–120  
ATTENUATION = 0dB  
ATTENUATION = 12dB  
ATTENUATION = 21dB  
ATTENUATION = 33dB  
ATTENUATION = 47dB  
0
3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
OUTPUT P1dB (dBm)  
Figure 11. 2× LO Carrier Feedthrough vs. LO Frequency, Attenuation,  
Supply, and Temperature  
Figure 14. Output P1dB Compression Point Distribution at Nominal  
and Worst-Case Conditions  
10  
1.0  
30  
28  
26  
24  
22  
20  
18  
16  
14  
12  
5
0.5  
1dB  
COMPRESSION  
POINT  
0
0
–5  
–0.5  
–1.0  
–1.5  
–2.0  
–2.5  
–10  
–15  
–20  
–25  
10  
0.1  
1
10  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
DIFFERENTIAL INPUT VOLTAGE (V p-p)  
LO FREQUENCY (MHz)  
Figure 15. Output IP3 vs. LO Frequency at Nominal Conditions  
Figure 12. Output P1dB Compression Point at Worst-Case LO Frequency  
vs. Supply and Temperature  
10.5  
10.0  
9.5  
9.0  
8.5  
8.0  
7.5  
7.0  
6.5  
50  
NOMINAL  
WORST CASE  
45  
40  
35  
30  
25  
20  
15  
10  
5
6.0  
0
15  
16  
17  
18  
19  
20  
21  
22  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
OUTPUT IP3 (dBm)  
Figure 13. Output P1dB Compression Point vs. LO Frequency at  
Nominal Conditions  
Figure 16. Output IP3 Distribution at Nominal and Worst-Case  
Conditions  
Rev. B | Page 14 of 48  
Data Sheet  
ADRF6755  
–145  
–147  
–149  
–151  
–153  
–155  
–157  
–159  
–161  
–163  
–165  
–60  
ATTENUATION = 21dB  
–70  
ATTENUATION = 0dB  
–80  
–90  
–100  
–110  
–120  
ATTENUATION = 47dB  
–130  
–25  
–20  
–15  
–10  
–5  
0
5
10  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
OUTPUT POWER (dBm)  
LO FREQUENCY (MHz)  
Figure 20. Noise Floor at 0 dB Attenuation vs. Output Power  
at Nominal Conditions  
Figure 17. LO Off Isolation vs. LO Frequency, Attenuation, Supply,  
and Temperature  
–30  
100  
ATTENUATION  
= 21dB (dBc/Hz)  
–40  
–50  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
ATTENUATION = 0dB  
–60  
ATTENUATION  
= 0dB (dBc/Hz)  
–70  
–80  
–90  
ATTENUATION  
= 21dB (dBm/Hz)  
–100  
–110  
–120  
–130  
ATTENUATION = 47dB  
ATTENUATION  
= 47dB (dBm/Hz)  
ATTENUATION = 21dB  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
–180 –176 –172 –168 –164 –160 –156 –152 –148 –144 –140  
LO FREQUENCY (MHz)  
NOISE FLOORAT 10MHz OFFSET FREQUENCY (dBm/Hz) AND (dBc/Hz)  
Figure 18. 2 × LO Off Isolation vs. LO Frequency, Attenuation, Supply,  
and Temperature  
Figure 21. Noise Floor at 10 MHz Offset Frequency Distribution at  
Worst-Case Conditions and Different Attenuation Settings  
–40  
1.0  
0.5  
UPPER THIRD  
HARMONIC (fLO + 3 × fBB  
)
–50  
–60  
0
–0.5  
–1.0  
–1.5  
–2.0  
–2.5  
–3.0  
–3.5  
–4.0  
UPPER SECOND  
HARMONIC (fLO + 2 × fBB  
)
–70  
–80  
–90  
–100  
–110  
–120  
LOWER SECOND  
HARMONIC (fLO – 2 × fBB  
)
LOWER THIRD  
HARMONIC (fLO – 3 × fBB  
)
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
1
10  
100  
1000  
I AND Q BASEBAND INPUT FREQUENCY (MHz)  
Figure 19. Second-Order and Third-Order Harmonic Distortion vs.  
LO Frequency, Supply, and Temperature  
Figure 22. Normalized I and Q Input Bandwidth  
Rev. B | Page 15 of 48  
ADRF6755  
Data Sheet  
–10  
–12  
–14  
–16  
–18  
–20  
–22  
–24  
–26  
–28  
0
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
LOWER  
SIDEBAND  
3 × LO  
ATTENUATION = 0dB  
HARMONIC  
5 × LO  
HARMONIC  
4 × LO  
HARMONIC  
2 × LO  
HARMONIC  
ATTENUATION = 21dB AND 47dB  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
0
1
2
3
4
5
6
7
8
9
10  
OUTPUT FREQUENCY (MHz)  
FREQUENCY (MHz)  
Figure 23. Output Return Loss at Different Attenuation Settings vs. Output  
Frequency, Supply, and Temperature  
Figure 26. RF Output Spectral Plot over a Wide Span  
–60  
–70  
0
LO FREQUENCY = 2400MHz  
LO FREQUENCY = 1200MHz  
LO FREQUENCY = 580MHz  
LO FREQUENCY = 290MHz  
LO FREQUENCY = 100MHz  
–10  
LOWER  
SIDEBAND  
–80  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–90  
CARRIER  
FEEDTHROUGH  
–100  
–110  
–120  
–130  
–140  
–150  
–160  
SUPPRESSED  
SIDEBAND  
THIRD  
HARMONIC  
SECOND  
HARMONIC  
100  
1k  
10k  
100k  
1M  
10M  
1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880  
OFFSET FREQUENCY (Hz)  
FREQUENCY (MHz)  
Figure 24. RF Output Spectral Plot over a 10 MHz Span  
Figure 27. Phase Noise Performance vs. LO Frequency, Nominal Conditions  
0
–60  
–70  
LOWER  
SIDEBAND  
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–80  
LO FREQUENCY = 2500MHz  
–90  
CARRIER  
FEEDTHROUGH  
–100  
–110  
–120  
–130  
SUPPRESSED  
SIDEBAND  
THIRD  
HARMONIC  
–140  
LO FREQUENCY = 100MHz  
–150  
–160  
1825 1835 1845 1855 1865 1875 1885 1895 1905 1915 1925  
100  
1k  
10k  
100k  
1M  
10M  
FREQUENCY (MHz)  
OFFSET FREQUENCY (Hz)  
Figure 28. Phase Noise Performance vs. LO Frequency, Supply,  
and Temperature  
Figure 25. RF Output Spectral Plot over a 100 MHz Span  
Rev. B | Page 16 of 48  
Data Sheet  
ADRF6755  
–60  
–70  
–60  
900MHz PHASE NOISE (dBc/Hz)  
1800MHz PHASE NOISE (dBc/Hz)  
2100MHz PHASE NOISE (dBc/Hz)  
–70  
–80  
–80  
–90  
–90  
–100  
–110  
–120  
–130  
–140  
–150  
–160  
–100  
–110  
–120  
–130  
–140  
–150  
–160  
100  
1k  
10k  
100k  
1M  
10M  
100  
1k  
10k  
100k  
1M  
10M  
OFFSET FREQUENCY (Hz)  
OFFSET FREQUENCY (Hz)  
Figure 29. Phase Noise Performance Distribution at Worst-Case Conditions  
Figure 32. Phase Noise Performance vs. LO Frequency, Nominal Conditions  
with Narrow Loop Bandwidth  
0.50  
0.45  
0.40  
0.35  
0.30  
0.25  
0.20  
0.15  
0.10  
0.05  
–50  
–55  
–60  
–65  
–70  
–75  
–80  
+25°C 5V MAX SPUR  
+85°C 4.75V MAX SPUR  
+85°C 5.25V MAX SPUR  
–40°C 4.75V MAX SPUR  
–40°C 5.25V MAX SPUR  
–85  
0
–90  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
LO FREQUENCY (MHz)  
Figure 30. Integrated Phase Noise over an Integration Bandwidth of 1 kHz to  
8 MHz vs. LO Frequency at Nominal Conditions  
Figure 33. Integer Boundary Spur Performance vs. LO Frequency,  
Supply, and Temperature  
90  
–50  
1875MHz  
REFERENCE SPURS AT 80MHz OFFSET  
PFD SPURS AT 40MHz OFFSET  
2310MHz  
80  
–60  
70  
60  
50  
40  
30  
20  
10  
0
–70  
–80  
–90  
–100  
–110  
0.10  
0.15  
0.20  
0.25  
0.30  
0.35  
0.40  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
RMS JITTER (Degrees)  
LO FREQUENCY (MHz)  
Figure 34. Spurs > 10 MHz from Carrier vs. LO Frequency,  
Supply, and Temperature  
Figure 31. Integrated Phase Noise Distribution over an Integration  
Bandwidth of 1 kHz to 8 MHz at 1875 MHz and 2310 MHz  
Rev. B | Page 17 of 48  
ADRF6755  
Data Sheet  
1G  
100M  
10M  
1M  
60  
50  
40  
30  
20  
10  
0
NOMINAL  
WORST CASE  
100k  
10k  
ACQUISITION  
TO 100Hz  
1k  
START OF  
ACQUISITION  
100  
10  
1
LDET  
NUMBER OF PFD  
CYCLES TO DECLARE  
LDET = 4096  
0.1  
–50 –30 –10 10 30 50 70 90 110 130 150 170 190 210 230 250  
–1.0 –0.8 –0.6 –0.4 –0.2  
0
0.2  
0.4  
0.6  
0.8  
1.0  
TIME (µs)  
ATTENUATOR RELATIVE STEP ACCURACY (dB)  
Figure 35. PLL Frequency Settling Time at Worst-Case LO Frequency  
with Lock Detect Shown  
Figure 38. Attenuator Relative Step Accuracy Distribution at Nominal  
and Worst-Case Conditions, LO > 300 MHz, All Attenuation Steps  
5
0
14  
NOMINAL  
WORST CASE  
12  
10  
8
–5  
–10  
–15  
–20  
–25  
–30  
–35  
–40  
–45  
6
4
2
–50  
0
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
–3.25  
–2.25  
–1.25  
–0.25  
0.25  
0.75  
1.75  
2.75  
–2.75 –1.75  
–0.75  
1.25  
2.25  
3.25  
LO FREQUENCY (MHz)  
ATTENUATOR RELATIVE STEP ACCURACY ACROSS  
FULL OUTPUT FREQUENCY RANGE (dB)  
Figure 36. Attenuator Gain vs. LO Frequency by Gain Code, All Attenuator  
Code Steps  
Figure 39. Attenuator Relative Step Accuracy Across Full Output  
Frequency Range Distribution at Nominal and Worst-Case Conditions,  
LO > 300 MHz, All Attenuation Steps  
2
1.0  
0.5  
0
–2  
–4  
–6  
–8  
0
–0.5  
–1.0  
–10  
–1.5  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
LO FREQUENCY (MHz)  
Figure 40. Attenuator Absolute Step Accuracy over all Attenuation Steps  
vs. LO Frequency, Nominal Conditions  
Figure 37. Attenuator Relative Step Accuracy over all Attenuation Steps  
vs. LO Frequency, Nominal Conditions  
Rev. B | Page 18 of 48  
 
 
 
Data Sheet  
ADRF6755  
10  
9
8
7
6
5
4
3
2
1
0
30  
25  
20  
15  
10  
5
NOMINAL  
WORST CASE  
0
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
–5.0 –4.6 –4.2 –3.8 –3.4 –3.0 –2.6 –2.2 –1.8 –1.4 –1.0 –0.6 –0.2 0.2  
STARTING ATTENUATOR STEP  
ATTENUATOR ABSOLUTE STEP ACCURACY (dB)  
Figure 44. Attenuator Settling Time to 0.5 dB for Small Steps  
(1 dB to 6 dB) at Nominal Conditions  
Figure 41. Attenuator Absolute Step Accuracy Distribution at Nominal  
and Worst-Case Conditions, LO > 300 MHz, All Attenuation Steps  
2.0  
1.5  
20  
18  
16  
14  
12  
10  
8
1.0  
0.5  
0
–0.5  
–1.0  
–1.5  
6
4
2
–2.0  
0
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
LO FREQUENCY (MHz)  
STARTING ATTENUATOR STEP  
Figure 42. Gain Flatness in any 40 MHz for all Attenuation Steps vs.  
LO Frequency at Nominal Conditions  
Figure 45. Attenuator Settling Time to 0.2 dB for Large Steps  
(7 dB to 47 dB) at Nominal Conditions  
10  
9
8
7
6
5
4
3
2
1
0
20  
18  
16  
14  
12  
10  
8
6
4
2
0
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
STARTING ATTENUATOR STEP  
STARTING ATTENUATOR STEP  
Figure 46. Attenuator Settling Time to 0.5 dB for Large Steps  
(7 dB to 47 dB) at Nominal Conditions  
Figure 43. Attenuator Setting Time to 0.2 dB for Small Steps (1 dB to 6 dB) at  
Nominal Conditions  
Rev. B | Page 19 of 48  
ADRF6755  
Data Sheet  
100  
50  
45  
40  
35  
30  
25  
20  
15  
10  
5
NOMINAL SETTLING TIME TO 0.2dB  
NOMINAL SETTLING TIME TO 0.2dB  
WORST CASE SETTLING TIME TO 0.2dB  
NOMINAL SETTLING TIME TO 0.5dB  
WORST CASE SETTLING TIME TO 0.5dB  
WORST CASE SETTLING TIME TO 0.2dB  
NOMINAL SETTLING TIME TO 0.5dB  
WORST CASE SETTLING TIME TO 0.5dB  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
0
0
0.5  
1.0  
1.5  
2.0  
2.5  
3.0  
3.5  
4.0  
4.5  
5.0  
0
3
6
9
12  
15  
18  
21  
24  
27  
30  
33  
ATTENUATOR SETTLING TIME (µs)  
ATTENUATOR SETTLING TIME (µs)  
Figure 47. Attenuator Settling Time to 0.2 dB and 0.5 dB Distribution at  
Nominal and Worst-Case Conditions for Typical Small Step  
Figure 50. Attenuator Settling Time to 0.2 dB and 0.5 dB Distribution at  
Nominal and Worst-Case Conditions for Worst-Case Large Step  
(47 dB to 0 dB)  
100  
0
NOMINAL SETTLING TIME TO 0.2dB  
WORST CASE SETTLING TIME TO 0.2dB  
90  
NOMINAL SETTLING TIME TO 0.5dB  
–10  
WORST CASE SETTLING TIME TO 0.5dB  
80  
–20  
70  
60  
50  
40  
30  
20  
10  
0
TURN-ON = 180ns  
–30  
TURN-OFF= 350ns  
–40  
–50  
–60  
TXDIS  
–70  
0
3
6
9
12  
15  
18  
21  
24  
0
1
2
3
4
5
6
7
8
ATTENUATOR SETTLING TIME (µs)  
TXDIS SETTLING TIME (μs)  
Figure 48. Attenuator Settling Time to 0.2 dB and 0.5 dB Distribution at  
Nominal and Worst-Case Conditions for Worst-Case Small Step (36 dB to 42 dB)  
Figure 51. TXDIS Settling Time at Worst-Case Supply  
and Temperature  
100  
NOMINAL SETTLING TIME TO 0.2dB  
WORST CASE SETTLING TIME TO 0.2dB  
90  
NOMINAL SETTLING TIME TO 0.5dB  
WORST CASE SETTLING TIME TO 0.5dB  
80  
70  
60  
50  
40  
30  
20  
10  
0
0
3
6
9
12  
15  
18  
21  
ATTENUATOR SETTLING TIME (µs)  
Figure 49. Attenuator Settling Time to 0.2 dB and 0.5 dB Distribution at  
Nominal and Worst-Case Conditions for Typical Large Step  
Rev. B | Page 20 of 48  
Data Sheet  
ADRF6755  
THEORY OF OPERATION  
FROM  
REFIN  
PIN  
OVERVIEW  
TO  
PFD  
×2  
5-BIT  
÷2  
DOUBLER  
R-DIVIDER  
The ADRF6755 device can be divided into the following basic  
building blocks:  
Figure 53. Reference Input Path  
The PFD frequency equation is  
PFD = fREFIN × [(1 + D)/(R × (1 + T))]  
where:  
REFIN is the reference input frequency.  
D is the doubler bit.  
PLL synthesizer and VCO  
Quadrature modulator  
Attenuator  
f
(1)  
Voltage regulator  
f
I2C/SPI interface  
R is the programmed divide ratio of the binary 5-bit  
programmable reference divider (1 to 32).  
T is the R/2 divider setting bit (CR10[6] = 0 or 1).  
Each of these building blocks is described in detail in the  
sections that follow.  
PLL SYNTHESIZER AND VCO  
Overview  
If no division is required, it is recommended that the 5-bit  
R-divider and the divide-by-2 be disabled by setting CR5[4] = 0.  
If an even numbered division is required, enable the divide-by-2  
by setting CR5[4] = 1 and CR10[6] = 1 and implement the  
remainder of the division in the 5-bit R-divider. If an odd number  
division is required, set CR5[4] = 1 and implement all of the  
division in the 5-bit R-divider.  
The phase-locked loop (PLL) consists of a fractional-N frequency  
synthesizer with a 25-bit fixed modulus, allowing a frequency  
resolution of less than 1 Hz over the entire frequency range. It  
also has an integrated voltage-controlled oscillator (VCO) with  
a fundamental output frequency ranging from 2310 MHz to  
4800 MHz. An RF divider, controlled by Register CR28,  
Bits[2:0], extends the lower limit of the local oscillator (LO)  
frequency range to 100 MHz. See Table 6 for more details on  
Register CR28.  
RF Fractional-N Divider  
The RF fractional-N divider allows a division ratio in the PLL  
feedback path that can range from 23 to 4095. The relationship  
between the fractional-N divider and the LO frequency is  
described in the INT and FRAC Relationship section.  
Reference Input Section  
The reference input stage is shown Figure 52. SW1 and SW2 are  
normally closed switches. SW3 is normally open. When power-  
down is initiated, SW3 is closed, and SW1 and SW2 are open. This  
ensures that there is no loading of the REFIN pin at power-down.  
INT and FRAC Relationship  
The integer (INT) and fractional (FRAC) values make it possible to  
generate output frequencies that are spaced by fractions of the  
phase frequency detector (PFD) frequency. See the Example—  
Changing the LO Frequency section for more information.  
POWER-DOWN  
CONTROL  
The LO frequency equation is  
100kΩ  
SW2  
NC  
LO = fPFD × (INT + (FRAC/225))/2RFDIV  
where:  
LO is the local oscillator frequency.  
PFD is the PFD frequency.  
(2)  
TO  
R-DIVIDER  
REFIN  
NC  
SW1  
BUFFER  
SW3  
NC  
f
Figure 52. Reference Input Stage  
INT is the integer component of the required division factor  
and is controlled by the CR6 and CR7 registers.  
Reference Input Path  
FRAC is the fractional component of the required division  
factor and is controlled by the CR0 to CR3 registers.  
RFDIV is set in Register CR28, Bits[2:0], and controls the  
setting of the divider at the output of the PLL.  
The on-chip reference frequency doubler allows the input  
reference signal to be doubled. This is useful for increasing the  
PFD comparison frequency. Making the PFD frequency higher  
improves the noise performance of the system. Doubling the  
PFD frequency usually improves the in-band phase noise  
performance by up to 3 dBc/Hz.  
25  
RF N-DIVIDER  
N-COUNTER  
N = INT + FRAC/2  
TO  
PFD  
FROM VCO  
OUTPUT  
DIVIDERS  
The 5-bit R-divider allows the input reference frequency (REFIN) to  
be divided down to produce the reference clock to the PFD.  
Division ratios from 1 to 32 are allowed.  
THIRD-ORDER  
FRACTIONAL  
INTERPOLATOR  
INT  
REG  
FRAC  
VALUE  
An additional divide-by-2 (÷2) function in the reference input  
path allows for a greater division range.  
Figure 54. RF Fractional-N Divider  
Rev. B | Page 21 of 48  
 
 
 
 
 
 
 
ADRF6755  
Data Sheet  
2.5  
2.3  
2.1  
1.9  
1.7  
1.5  
1.3  
1.1  
0.9  
0.7  
0.5  
Phase Frequency Detector (PFD) and Charge Pump  
The PFD takes inputs from the R-divider and the N-counter and  
produces an output proportional to the phase and frequency differ-  
ence between them (see Figure 55 for a simplified schematic).  
The PFD includes a fixed delay element that sets the width of  
the antibacklash pulse, ensuring that there is no dead zone in  
the PFD transfer function.  
UP  
HI  
D1  
Q1  
U1  
+IN  
CLR1  
CHARGE  
PUMP  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
CP  
DELAY  
DOWN  
U3  
LO FREQUENCY (MHz)  
Figure 56. VTUNE vs. LO Frequency  
The VCO displays a variation of KVCO as VTUNE varies within the  
band and from band to band. Figure 57 shows how KVCO varies  
across the full frequency range. Figure 57 is useful when  
calculating the loop filter bandwidth and individual loop filter  
components using ADISimPLL™. ADISimPLL is an Analog  
Devices, Inc., simulator that aids in PLL design, particularly  
with respect to the loop filter. It reports parameters such as phase  
noise, integrated phase noise, and acquisition time for a  
particular set of input conditions. ADISimPLL can be  
downloaded from www.analog.com/adisimpll.  
CLR2  
D2 Q2  
HI  
U2  
–IN  
Figure 55. PFD Simplified Schematic  
Lock Detect (LDET)  
LDET (Pin 44) signals when the PLL has achieved lock to an  
error frequency of less than 100 Hz. On a write to Register CR0,  
a new PLL acquisition cycle starts, and the LDET signal goes  
low. When lock has been achieved, this signal returns high.  
40  
Voltage-Controlled Oscillator (VCO)  
The VCO core in the ADRF6755 consists of three separate VCOs,  
each with 16 overlapping bands. This configuration of 48 bands  
allows the VCO frequency range to extend from 2310 MHz to  
4800 MHz. The three VCOs are divided by a programmable  
divider, RFDIV, controlled by Register CR28, Bits[2:0]. This  
divider provides divisions of 1, 2, 4, 8, and 16 to ensure that the  
frequency range is extended from 144.375 MHz (2310 MHz/16)  
to 4800 MHz (4800 MHz/1). A divide-by-2 quadrature circuit in  
the path to the modulator then provides the full LO frequency  
range from 100 MHz to 2400 MHz.  
30  
20  
10  
0
Figure 56 shows a sweep of VTUNE vs. LO frequency demonstrating  
the three VCOs overlapping and the multiple overlapping bands  
within each VCO at the LO frequency range of 100 MHz to  
2400 MHz. Note that Figure 56 includes the RFDIV being  
incorporated to provide further divisions of the fundamental VCO  
frequency; thus, each VCO is used on multiple different occasions  
throughout the full LO frequency range. The choice of three  
16-band VCOs and an RFDIV allows the wide frequency range to  
be covered without large VCO sensitivity (KVCO) or resultant  
poor phase noise and spurious performance.  
100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500  
LO FREQUENCY (MHz)  
Figure 57. KVCO vs. LO Frequency  
Autocalibration  
The correct VCO and band are chosen automatically by the  
VCO and band select circuitry when Register CR0 is updated.  
This is referred to as autocalibration. The autocalibration time  
is set by Register CR25.  
Autocalibration Time = (BSCDIV × 28)/PFD  
(3)  
where:  
BSCDIV = Register CR25, Bits[7:0].  
PFD = PFD frequency.  
For a PFD frequency of 40 MHz, set BSCDIV = 100 to set an  
autocalibration time of 70 µs.  
Rev. B | Page 22 of 48  
 
 
 
 
Data Sheet  
ADRF6755  
Note that BSCDIV must be recalculated if the PFD frequency is  
changed. The recommended autocalibration setting is 70 µs.  
During this time, the VCO VTUNE is disconnected from the output  
of the loop filter and is connected to an internal reference voltage.  
A typical frequency acquisition is shown in Figure 58.  
1G  
Programming the Correct LO Frequency  
There are two steps to programming the correct LO frequency.  
The user must calculate the RFDIV value based on the required  
LO frequency and PFD frequency, and the N-divider ratio that  
is required in the PLL.  
1. Calculate the value of RFDIV, which is used to program  
Register CR28, Bits[2:0] and CR27, Bit 4 from the  
following lookup table, Table 6.  
100M  
10M  
1M  
Table 6. RFDIV Lookup Table  
AUTOCAL  
100k  
10k  
1k  
TIME (μs)  
CR28[2:0]  
= RFDIV  
LO Frequency (MHz)  
1155 < LO < 2400  
RFDIVIDER  
Divide-by-1  
Divide-by-2  
Divide-by-4  
Divide-by-8  
Divide-by-16  
CR27[4]  
ACQUISITION TO 100Hz  
000  
1
0
0
0
0
100  
10  
577.5 < LO ≤ 1155  
288.75 < LO ≤ 577.5  
144.375 < LO ≤ 288.75  
100 < LO ≤ 144.375  
001  
010  
011  
1
100  
0.1  
0
25  
50  
75  
100 125 150 175 200 225 250  
TIME (µs)  
2. Using the following equation, calculate the value of the  
N-divider:  
Figure 58. PLL Acquisition  
N = (2RFDIV × LO)/fPFD  
(4)  
After autocalibration, normal PLL action resumes, and the  
correct frequency is acquired to within a frequency error of  
100 Hz in 170 μs typically. For a maximum cumulative step of  
100 kHz/2RFDIV, autocalibration can be turned off by setting  
Register CR24, Bit 0 = 1. This enables cumulative PLL acquisi-  
tions of ≤100 kHz (for RFDIV = ÷1, 50 kHz for RFDIV = ÷2,  
and so on) to occur without the autocalibration procedure,  
which improves acquisition times significantly (see Figure 59).  
1M  
where:  
N is the N-divider value.  
RFDIV is the setting in Register CR28, Bits[2:0].  
LO is the local oscillator frequency.  
f
PFD is the PFD frequency.  
This equation is a different representation of Equation 2.  
Example to Program the Correct LO Frequency  
Assume that the PFD frequency is 40 MHz and that the  
required LO frequency is 1875 MHz.  
From Table 6, 2RFDIV = 1 (RFDIV = 0)  
100k  
10k  
1k  
N = (1 × 1875 × 106)/(40 × 106) = 46.875  
The N-divider value is composed of integer (INT) and  
fractional (FRAC) components according to the following  
equation:  
ACQUISITION TO 100Hz  
100  
N = INT + FRAC/225  
(5)  
10  
1
INT = 46 and FRAC = 29,360,128  
The appropriate registers must then be programmed according to  
the register map. The order in which the registers are programmed  
is important. Writing to CR0 initiates a PLL acquisition cycle.  
If the programmed LO frequency requires a change in the value  
of CR27[4] (see Table 6), CR27 should be the last register  
programmed, preceded by CR0. If the programmed LO frequency  
does not require a change in the value of CR27[4], it is optional  
to omit the write to CR27 and, in that case, CR0 should be the  
last register programmed.  
0
50  
100  
150  
200  
TIME (μs)  
Figure 59. PLL Acquisition Without Autocalibration for a 100 kHz Step  
Rev. B | Page 23 of 48  
 
 
 
ADRF6755  
Data Sheet  
differential termination is recommended at the baseband inputs,  
and this dominates the input impedance as seen by the input  
baseband signal. This ensures that the input impedance, as seen by  
the input circuit, remains flat across the baseband bandwidth.  
See Figure 62 for a typical configuration.  
QUADRATURE MODULATOR  
Overview  
A basic block diagram of the ADRF6755 quadrature modulator  
circuit is shown in Figure 60. The VCO/RFDIVIDER generates  
a signal at the 2× LO frequency, which is then divided down to give  
a signal at the LO frequency. This signal is then split into in-phase  
and quadrature components to provide the LO signals that drive  
the mixers.  
CURRENT OUTPUT DAC  
(EXAMPLE: AD9779)  
ADRF6755  
OUT1_P  
IBB  
50Ω  
50Ω  
LOW-  
PASS  
V-TO-I  
100Ω  
100Ω  
FILTER  
IBB  
IBB  
OUT1_N  
OUT2_N  
IBB  
QBB  
50Ω  
50Ω  
LOW-  
PASS  
FILTER  
QUAD  
RFOUT TO  
ATTENUATOR  
÷2  
RF DIVIDER  
V-TO-I  
VCO  
PHASE  
SPLITTER  
QBB  
OUT2_P  
Figure 62. Typical Baseband Input Configuration  
QBB  
QBB  
The swing of the AD9779 output currents ranges from 0 mA to  
20 mA. The ac voltage swing is 1 V p-p single-ended or 2 V p-p  
differential with the 50 Ω resistors in place. The 100 Ω differen-  
tial termination resistors at the baseband inputs have the effect  
of limiting this swing without changing the dc bias condition of  
500 mV. The low-pass filter is used to filter the DAC outputs  
and remove images when driving a modulator.  
Figure 60. Block Diagram of the Quadrature Modulator  
The I and Q baseband input signals are converted to currents by  
the V-to-I stages, which then drive the two mixers. The outputs  
of these mixers combine to feed the single-ended output. This  
single-ended output is then fed to the attenuator and, finally, to  
the external RFOUT signal pin.  
Baseband Inputs  
Another consideration is that the baseband inputs actually source a  
current of 240 μA out of each of the four inputs. This current must  
be taken into account when setting up the dc bias of 500 m V. In  
the initial example based on Figure 61, an error of 12 mV occurs  
due to the 240 μA current flowing through the 50 Ω resistor.  
Analog Devices recommends that the accuracy of the dc bias  
should be 500 mV 25 mV. It is also important that this 240 μA  
current have a dc path to ground.  
The baseband inputs, QBB,  
, IBB, and  
, must be driven  
IBB  
QBB  
from a differential source. The nominal drive level of 0.9 V p-p  
differential (450 mV p-p on each pin) should be biased to a  
common-mode level of 500 mV dc.  
To set the dc bias level at the baseband inputs, refer to Figure 61.  
The average output current on each of the AD9779 outputs is  
10 mA. A current of 10 mA flowing through each of the 50 Ω  
resistors to ground produces the desired dc bias of 500 mV at  
each of the baseband inputs.  
Optimization  
The carrier feedthrough and the sideband suppression  
performance of the ADRF6755 can be improved over the  
specifications in Table 1 by using the following optimization  
techniques.  
CURRENT OUTPUT DAC  
(EXAMPLE: AD9779)  
ADRF6755  
OUT1_P  
IBB  
50Ω  
50Ω  
Carrier Feedthrough Nulling  
Carrier feedthrough results from dc offsets that occur between  
the P and N inputs of each of the differential baseband inputs.  
Normally these inputs are set to a dc bias of approximately 500 m V.  
OUT1_N  
OUT2_N  
IBB  
QBB  
50Ω  
50Ω  
However, if a dc offset is introduced between the P and N inputs of  
either or both I and Q inputs, the carrier feedthrough is affected  
in either a positive or a negative fashion. Note that the dc bias  
level remains at 500 mV (average P and N level). The I channel  
offset is often held constant while the Q channel offset is varied  
until a minimum carrier feedthrough level is obtained. Then,  
while retaining the new Q channel offset, the I channel offset is  
adjusted until a new minimum is reached. This is usually per-  
formed at a single frequency and, thus, is not optimized over  
the complete frequency range. Multiple optimizations at different  
QBB  
OUT2_P  
Figure 61. Establishing DC Bias Level on Baseband Inputs  
The differential baseband inputs (QBB,  
,
, and IBB)  
QBB IBB  
consist of the bases of PNP transistors, which present a high  
impedance of about 30 kΩ in parallel with approximately 2 pF  
of capacitance. The impedance is approximately 30 kΩ below  
1 MHz and starts to roll off at higher frequency. A 100 Ω  
Rev. B | Page 24 of 48  
 
 
 
 
Data Sheet  
ADRF6755  
frequencies must be performed to ensure optimum carrier feed-  
through across the full frequency range.  
the CS pin (Pin 27). Bits[4:0] of the slave address are set to all  
0s. The slave address consists of the seven MSBs of an 8-bit  
word. The LSB of the word sets either a read or a write operation  
(see Figure 63). Logic 1 corresponds to a read operation, whereas  
Logic 0 corresponds to a write operation.  
Sideband Suppression Nulling  
Sideband suppression results from relative gain and relative phase  
offsets between the I channel and Q channel and can be optimized  
through adjustments to those two parameters. Adjusting only  
one parameter improves the sideband suppression only to a  
point. For optimum sideband suppression, an iterative adjustment  
between phase and amplitude is required.  
To control the device on the bus, the following protocol must  
be followed. The master initiates a data transfer by establishing  
a start condition, defined by a high-to-low transition on SDA  
while SCL remains high. This indicates that an address/data  
stream follows. All peripherals respond to the start condition  
and shift the next eight bits (the 7-bit address and the R/W bit).  
The bits are transferred from MSB to LSB. The peripheral that  
recognizes the transmitted address responds by pulling the data  
line low during the ninth clock pulse. This is known as an  
acknowledge bit. All other devices then withdraw from the bus  
and maintain an idle condition. During the idle condition, the  
device monitors the SDA and SCL lines waiting for the start  
condition and the correct transmitted address. The R/W bit  
determines the direction of the data. Logic 0 on the LSB of the  
first byte indicates that the master writes information to the  
peripheral. Logic 1 on the LSB of the first byte indicates that the  
master reads information from the peripheral.  
ATTENUATOR  
The digital attenuator consists of six attenuation blocks: 1 dB,  
2 dB, 4 dB, 8 dB, and two 16 dB blocks; each is separately  
controlled. Each attenuation block consists of field effect transistor  
(FET) switches and resistors that form either a pi-shaped or a  
T-shaped attenuator. By controlling the states of the FET switches  
through the control lines, each attenuation block can be set to  
the pass state (0 dB) or the attenuation state (1 dB to 47 dB).  
The various combinations of the six blocks provide the  
attenuation states from 0 dB to 47 dB in 1 dB increments.  
VOLTAGE REGULATOR  
The voltage regulator is powered from a 5 V supply that is  
provided by VCC1 (Pin 11) and produces a 3.3 V nominal  
regulated output voltage, REGOUT, on Pin 12. This pin must  
be connected (external to the IC) to the VREG1 through VREG6  
package pins.  
The ADRF6755 acts as a standard slave device on the bus. The data  
on the SDA pin (Pin 29) is eight bits long, supporting the 7-bit  
addresses plus the R/W bit. The ADRF6755 has 34 subaddresses  
to enable the user-accessible internal registers. Therefore, it  
interprets the first byte as the device address and the second  
byte as the starting subaddress. Auto-increment mode is supported,  
which allows data to be read from or written to the starting sub-  
address and each subsequent address without manually addressing  
the subsequent subaddress. A data transfer is always terminated  
by a stop condition. The user can also access any unique subaddress  
register on a one-by-one basis without updating all registers.  
Decouple the regulator output (REGOUT) with a parallel  
combination of 10 pF and 220 µF capacitors. The 220 µF  
capacitor, which is recommended for best performance,  
decouples broadband noise, leading to better phase noise. Each  
VREGx pin should have the following decoupling capacitors:  
100 nF multilayer ceramic with an additional 10 pF in parallel,  
both placed as close as possible to the device under test (DUT)  
power supply pins. X7R or X5R capacitors are recommended.  
See the Evaluation Board section for more information.  
Stop and start conditions can be detected at any stage of the data  
transfer. If these conditions are asserted out of sequence with  
normal read and write operations, they cause an immediate jump  
to the idle condition. If an invalid subaddress is issued by the  
user, the ADRF6755 does not issue an acknowledge and returns to  
the idle condition. In a no acknowledge condition, the SDA line is  
not pulled low on the ninth pulse. See Figure 64 and Figure 65  
for sample write and read data transfers, Figure 66 for the timing  
protocol, and Figure 2 for a more detailed timing diagram.  
I2C INTERFACE  
The ADRF6755 supports a 2-wire, I2C-compatible serial bus  
that drives multiple peripherals. The serial data (SDA) and serial  
clock (SCL) inputs carry information between any devices that  
are connected to the bus. Each slave device is recognized by a  
unique address. The ADRF6755 has two possible 7-bit slave  
addresses for both read and write operations. The MSB of the  
7-bit slave address is set to 1. Bit A5 of the slave address is set by  
R/W  
CTRL  
SLAVE ADDRESS[6:0]  
1
A5  
0
0
0
0
0
X
MSB = 1 SET BY  
PIN 27  
0 = WR  
1 = RD  
(CS)  
Figure 63. Slave Address Configuration  
Rev. B | Page 25 of 48  
 
 
 
 
ADRF6755  
Data Sheet  
S
SLAVE ADDR, LSB = 0 (WR) A(S) SUBADDR A(S) DATA A(S)  
DATA A(S)  
P
S = START BIT  
P = STOP BIT  
A(S) = ACKNOWLEDGE BY SLAVE  
Figure 64. I2C Write Data Transfer  
S
SLAVE ADDR, LSB = 0 (WR) A(S) SUBADDR A(S)  
S
SLAVE ADDR, LSB = 1 (RD) A(S) DATA A(M)  
DATA A(M) P  
S = START BIT  
P = STOP BIT  
A(M) = NO ACKNOWLEDGE BY MASTER  
A(S) = ACKNOWLEDGE BY SLAVE  
A(M) = ACKNOWLEDGE BY MASTER  
Figure 65. I2C Read Data Transfer  
START BIT  
SDA  
STOP BIT  
SLAVE ADDRESS  
SUBADDRESS  
DATA  
A6  
A5  
A7  
A0  
D7  
D0  
SCL  
S
P
WR  
ACK  
ACK  
ACK  
SLAVE  
ADDR[4:0]  
SUBADDR[6:1]  
DATA[6:1]  
Figure 66. I2C Data Transfer Timing  
Rev. B | Page 26 of 48  
 
 
 
Data Sheet  
ADRF6755  
SPI Serial Interface Functionality  
SPI INTERFACE  
The SPI serial interface of the ADRF6755 consists of the CS,  
SDI (SDI/SDA), CLK (CLK/SCL), and SDO pins. CS is used to  
select the device when more than one device is connected to the  
serial clock and data lines. CLK is used to clock data in and out  
of the part. The SDI pin is used to write to the registers. The  
SDO pin is a dedicated output for the read mode. The part operates  
in slave mode and requires an externally applied serial clock to  
the CLK pin. The serial interface is designed to allow the part to be  
interfaced to systems that provide a serial clock that is synchronized  
to the serial data.  
The ADRF6755 also supports the SPI protocol. The part powers  
up in I2C mode but is not locked in this mode. To stay in I2C  
mode, it is recommended that the user tie the CS line to either  
3.3 V or GND, thus disabling SPI mode. It is not possible to lock  
the I2C mode, but it is possible to select and lock the SPI mode.  
To select and lock the SPI mode, three pulses must be sent to the  
CS pin, as shown in Figure 67. When the SPI protocol is locked  
in, it cannot be unlocked while the device is still powered up. To  
reset the serial interface, the part must be powered down and  
powered up again.  
Figure 68 shows an example of a write operation to the  
Serial Interface Selection  
ADRF6755. Data is clocked into the registers on the rising edge  
of CLK using a 24-bit write command. The first eight bits  
represent the write command, 0xD4; the next eight bits are the  
register address; and the final eight bits are the data to be written  
to the specific register. Figure 69 shows an example of a read  
operation. In this example, a shortened 16-bit write command is  
first used to select the appropriate register for a read operation,  
the first eight bits representing the write command, 0xD4, and  
the final eight bits representing the specific register. Then the  
CS line is pulsed low for a second time to retrieve data from the  
selected register using a 16-bit read command, the first eight  
bits representing the read command, 0xD5, and the final eight  
bits representing the contents of the register being read. Figure 3  
shows the timing for both SPI read and SPI write operations.  
The CS pin controls selection of the I2C or SPI interface.  
Figure 67 shows the selection process that is required to lock  
the SPI mode. To communicate with the part using the SPI  
protocol, three pulses must be sent to the CS pin. On the third  
rising edge, the part selects and locks the SPI protocol. Consistent  
with most SPI standards, the CS pin must be held low during all  
SPI communication to the part and held high at all other times.  
A
B
C
CS  
(STARTING  
HIGH)  
SPI LOCKED ON  
THIRD RISING EDGE  
SPI FRAMING  
EDGE  
CS  
(STARTING  
LOW)  
A
B
C
SPI LOCKED ON  
THIRD RISING EDGE  
SPI FRAMING  
EDGE  
Figure 67. Selecting the SPI Protocol  
Rev. B | Page 27 of 48  
 
 
ADRF6755  
Data Sheet  
• • •  
CS  
• • •  
CLK  
SDI  
• • •  
D0  
D7  
START  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
WRITE  
REGISTER  
ADDRESS  
COMMAND [0xD4]  
CS  
(CONTINUED)  
CLK  
(CONTINUED)  
SDI  
(CONTINUED)  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
STOP  
DATA  
BYTE  
Figure 68. SPI Byte Write Example  
• • •  
CS  
• • •  
CLK  
• • •  
SDI  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
D0  
D7  
D6  
D5  
D4  
D3  
D2  
D1  
START  
WRITE  
COMMAND [0xD4]  
REGISTER  
ADDRESS  
CS  
CLK  
SDI  
D7  
D6  
X
D5  
X
D4  
X
D3  
X
D2  
D1  
D0  
X
X
X
X
X
X
X
X
X
X
X
X
D7  
D6  
D5  
D4  
D3  
D2  
D1  
D0  
SDO  
STOP  
START  
READ  
COMMAND [0xD5]  
DATA  
BYTE  
Figure 69. SPI Byte Read Example  
Rev. B | Page 28 of 48  
 
 
Data Sheet  
ADRF6755  
Reference Input Path  
PROGRAM MODES  
The reference input path consists of a reference frequency doubler,  
a 5-bit reference divider, and a divide-by-2 function (see Figure 53).  
The doubler is programmed through Register CR10, Bit 5. The  
5-bit divider and divide-by-2 are enabled by programming  
Register CR5, Bit 4, and the division ratio is programmed through  
Register CR10, Bits[4:0]. The R/2 divider is programmed through  
Register CR10, Bit 6. Note that these registers are double-buffered.  
The ADRF6755 has 34 8-bit registers to allow program control  
of a number of functions. Either an SPI or an I2C interface can  
be used to program the register set. For details about the interfaces  
and timing, see Figure 63 to Figure 69. The registers are  
documented in Table 8 to Table 28.  
Several settings in the ADRF6755 are double-buffered. These  
settings include the FRAC value, the INT value, the 5-bit R-divider  
value, the reference frequency doubler, the R/2 divider, the RFDIV  
value, and the charge pump current setting. This means that  
two events must occur before the part uses a new value for any  
of the double-buffered settings. First, the new value is latched  
into the device by writing to the appropriate register. Next, a  
new write must be performed on Register CR0. When  
Charge Pump Current  
Register CR9, Bits[7:4], specify the charge pump current setting.  
With an RSET value of 4.7 kΩ, the maximum charge pump current is  
5 mA. The following equation applies:  
I
CPmax = 23.5/RSET  
The charge pump current has 16 settings from 312.5 μA to 5 mA.  
For the loop filter that is specified in the application solution, a  
charge pump current of 5 mA (Register CR9[7:4] = 0xF) gives a  
loop bandwidth of 100 kHz, which is the recommended loop  
bandwidth setting.  
Register CR0 is written, a new PLL acquisition takes place.  
For example, updating the fractional value involves a write to  
Register CR3, Register CR2, Register CR1, and Register CR0.  
Register CR3 should be written to first, followed by Register CR2  
and Register CR1, and, finally, Register CR0. The new acquisition  
begins after the write to Register CR0. Double buffering ensures  
that the bits written to do not take effect until after the write to  
Register CR0.  
Transmit Disable Control (TXDIS)  
The transmit disable control (TXDIS) is used to disable the RF out-  
put. TXDIS is normally held low. When asserted (brought high), it  
disables the RF output. Register CR14 is used to control which  
circuit blocks are powered down when TXDIS is asserted. To meet  
both the off isolation power specifications and the turn-on/  
turn-off settling time specifications, a value of 0x80 should be  
loaded into Register CR14. This effectively ensures that the  
attenuator is always enabled when TXDIS is asserted, even if other  
circuitry is disabled.  
12-Bit Integer Value  
Register CR7 and Register CR6 program the integer value (INT)  
of the feedback division factor (N); see Equation 5 for details.  
The INT value is a 12-bit number whose MSBs are programmed  
through Register CR7, Bits[3:0]. The LSBs are programmed  
through Register CR6, Bits[7:0]. The LO frequency setting is  
described by Equation 2. An alternative to this equation is  
provided by Equation 4, which details how to set the N-divider  
value. Note that these registers are double buffered.  
Power-Down/Power-Up Control Bits  
The four programmable power-up and power-down control bits  
are as follows:  
25-Bit Fractional Value  
Register CR12, Bit 2. Master power control bit for the PLL,  
including the VCO. This bit is normally set to a default value  
of 0 to power up the PLL.  
Register CR28, Bit 4. Controls the RFDIVIDER. This bit is  
normally set to a default value of 0 to power up the  
RFDIVIDER.  
Register CR3 to Register CR0 program the fractional value (FRAC)  
of the feedback division factor (N); see Equation 5 for details.  
The FRAC value is a 25-bit number whose MSB is programmed  
through Register CR3, Bit 0. The LSB is programmed through  
Register CR0, Bit 0. The LO frequency setting is described by  
Equation 2. An alternative to this equation is described by  
Equation 4, which details how to set the N-divider value. Note  
that these registers are double buffered.  
Register CR27, Bit 2. Controls the LO monitor outputs,  
LOMON and  
. The default is 0 when the monitor  
LOMON  
outputs are powered down. Setting this bit to 1 powers  
up the monitor outputs to one of four options, −6 dBm,  
−12 dBm, −18 dBm, or −24 dBm, as controlled by  
Register CR27, Bits[1:0].  
Register CR29, Bit 0. Controls the quadrature modulator  
power. The default is 0, which powers down the modulator.  
Write a 1 to this bit to power up the modulator.  
RFDIV Value  
The RFDIV value is dependent on the value of the LO frequency.  
The RFDIV value can be selected from the list in Table 6. Apply  
the selected RFDIV value to Equation 4, together with the LO  
frequency and PFD frequency values, to calculate the correct  
N-divider value.  
Rev. B | Page 29 of 48  
 
 
ADRF6755  
Data Sheet  
Lock Detect (LDET)  
The appropriate setting to use depends on the PFD frequency as  
well as the desired accuracy when LDET is declared. The LDET  
setting does not affect the acquisition time of the PLL. It only  
affects the time at which LDET goes high.  
Lock detect is enabled by setting Register CR23, Bit 4, to 1. The  
lock detect circuit is based on monitoring the up/down pulses  
from the PFD. As acquisition proceeds, the width of these  
pulses reduces until they are less than a target width (set by  
CR23[2]). At this point, a count of the number of successive  
PFD cycles is initiated, where the width of the up/down pulses  
remains less that the target width. When this count reaches a  
target count (set by CR13[6] and CR23[3]), LDET is set. The  
truth table for declaring LDET is given in Table 7.  
VCO Autocalibration  
The VCO uses an autocalibration technique to select the correct  
VCO and band, as explained in the Autocalibration section.  
Register CR24, Bit 0, controls whether the autocalibration is  
enabled. For normal operation, autocalibration must be enabled.  
However, if using cumulative frequency steps of 100 kHz/2RFDIV  
or less, autocalibration can be disabled by setting this bit to 1  
and then a new acquisition is initiated by writing to Register CR0.  
Table 7. Declaring LDET  
LDCount1  
CR13[6]  
LDCount0  
CR23[3]  
Number of PFD Cycles to  
Declare LDET  
Attenuator  
0
0
1
1
0
1
0
1
2048  
3072  
4096  
16,384  
The attenuator can be programmed from 0 dB to 47 dB in steps  
of 1 dB. Control is through Register CR30, Bits[5:0].  
Revision Readback  
The revision of the silicon die can be read back via Register CR33.  
Rev. B | Page 30 of 48  
 
 
 
Data Sheet  
ADRF6755  
REGISTER MAP  
REGISTER MAP SUMMARY  
Table 8. Register Map Summary  
Register Address (Hex)  
Register Name  
CR0  
CR1  
CR2  
CR3  
CR4  
CR5  
CR6  
CR7  
Type  
Description  
0x00  
0x01  
0x02  
0x03  
0x04  
0x05  
0x06  
0x07  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read/write  
Read only  
Read only  
Read only  
Fractional Word 4  
Fractional Word 3  
Fractional Word 2  
Fractional Word 1  
Reserved  
5-bit reference dividers enable  
Integer Word 2  
Integer Word 1 and MUXOUT control  
Reserved  
Charge pump current setting  
Reference frequency control  
Reserved  
PLL power-up  
Lock Detector Control 2  
TXDIS control  
Reserved  
Reserved  
Reserved  
Reserved  
Reserved  
Reserved  
Reserved  
Reserved  
Lock Detector Control 1  
Autocalibration  
Autocalibration Timer  
Reserved  
LO monitor output and LO selection  
LO selection  
Modulator  
Attenuator  
Reserved  
Reserved  
0x08  
0x09  
CR8  
CR9  
0x0A  
0x0B  
0x0C  
0x0D  
0x0E  
0x0F  
0x10  
0x11  
0x12  
0x13  
0x14  
0x15  
0x16  
0x17  
0x18  
0x19  
0x1A  
0x1B  
CR10  
CR11  
CR12  
CR13  
CR14  
CR15  
CR16  
CR17  
CR18  
CR19  
CR20  
CR21  
CR22  
CR23  
CR24  
CR25  
CR26  
CR27  
CR28  
CR29  
CR30  
CR31  
CR32  
CR33  
0x1C  
0x1D  
0x1E  
0x1F  
0x20  
0x21  
Revision code  
Rev. B | Page 31 of 48  
 
 
 
ADRF6755  
Data Sheet  
REGISTER BIT DESCRIPTIONS  
Table 9. Register CR0 (Address 0x00), Fractional Word 4  
Bit  
Table 13. Register CR5 (Address 0x05), 5-Bit Reference  
Divider Enable  
Description1  
Bit  
Description  
7
6
5
4
3
2
1
0
Fractional Word F7  
Fractional Word F6  
Fractional Word F5  
Fractional Word F4  
Fractional Word F3  
Fractional Word F2  
Fractional Word F1  
Fractional Word F0 (LSB)  
7
6
5
4
Set to 0  
Set to 0  
Set to 0  
5-bit R-divider and divide-by-2 enable1  
0 = disable 5-bit R-divider and divide-by-2 (default)  
1 = enable 5-bit R-divider and divide-by-2  
Set to 0  
Set to 0  
Set to 0  
Set to 0  
3
2
1
0
1 Double-buffered. Loaded on a write to Register CR0.  
Table 10. Register CR1 (Address 0x01), Fractional Word 3  
Bit  
Description1  
1 Double-buffered. Loaded on a write to Register CR0.  
7
6
5
4
3
2
1
0
Fractional Word F15  
Fractional Word F14  
Fractional Word F13  
Fractional Word F12  
Fractional Word F11  
Fractional Word F10  
Fractional Word F9  
Fractional Word F8  
Table 14. Register CR6 (Address 0x06), Integer Word 2  
Bit  
Description1  
7
6
5
4
3
2
1
0
Integer Word N7  
Integer Word N6  
Integer Word N5  
Integer Word N4  
Integer Word N3  
Integer Word N2  
Integer Word N1  
Integer Word N0  
1 Double-buffered. Loaded on a write to Register CR0.  
Table 11. Register CR2 (Address 0x02), Fractional Word 2  
Bit  
Description1  
1 Double-buffered. Loaded on a write to Register CR0.  
7
6
5
4
3
2
1
0
Fractional Word F23  
Fractional Word F22  
Fractional Word F21  
Fractional Word F20  
Fractional Word F19  
Fractional Word F18  
Fractional Word F17  
Fractional Word F16  
Table 15. Register CR7 (Address 0x07), Integer Word 1 and  
MUXOUT Control  
Bit  
Description  
[7:4]  
MUXOUT control  
0000 = tristate  
0001 = logic high  
0010 = logic low  
1101 = reference clock/2  
1110 = RF fractional-N divider clock/2  
Integer Word N111  
Integer Word N101  
Integer Word N91  
1 Double-buffered. Loaded on a write to Register CR0.  
3
2
1
0
Table 12. Register CR3 (Address 0x03), Fractional Word 1  
Bit  
Description  
7
Set to 0  
Integer Word N81  
6
Set to 0  
5
4
Set to 0  
Set to 0  
1 Double-buffered. Loaded on a write to Register CR0.  
3
Set to 0  
2
Set to 1  
1
0
Set to 0  
Fractional Word F24 (MSB)1  
1 Double-buffered. Loaded on a write to Register CR0.  
Rev. B | Page 32 of 48  
 
 
 
 
 
 
 
 
Data Sheet  
ADRF6755  
Table 16. Register CR9 (Address 0x09), Charge Pump  
Current Setting  
Table 18. Register CR12 (Address 0x0C), PLL Power-Up  
Bit  
Description  
Bit  
Description  
7
6
5
4
3
2
Set to 0  
Set to 0  
Set to 0  
Set to 1  
[7:4]  
Charge pump current1  
0000 = 0.3125 mA (default)  
0001 = 0.63 mA  
0010 = 0.94 mA  
0011 = 1.25 mA  
0100 = 1.57 mA  
0101 = 1.88 mA  
0110 = 2.19 mA  
0111 = 2.50 mA  
1000 = 2.81 mA  
1001 = 3.13 mA  
1010 = 3.44 mA  
1011 = 3.75 mA  
1100 = 4.06 mA  
1101 = 4.38 mA  
1110 = 4.69 mA  
1111 = 5.00 mA  
Set to 0  
Set to 1  
Power down PLL  
0 = power up PLL (default)  
1 = power down PLL  
Set to 0  
1
0
Set to 0  
Table 19. Register CR13 (Address 0x0D), Lock Detector Control 2  
Bit  
Description  
7
6
5
4
3
2
1
0
Set to 1  
LDCount1 (see Table 7)  
Set to 1  
Set to 0  
Set to 1  
Set to 0  
Set to 0  
Set to 0  
3
2
1
0
Set to 0  
Set to 0  
Set to 0  
Table 20. Register CR14 (Address 0x0E), TXDIS Control  
1 Double-buffered. Loaded on a write to Register CR0.  
Bit  
Description  
7
TXDIS_LOCLK  
0 = LO clock always running  
1 = stop LO clock when TXDIS = 1  
Table 17. Register CR10 (Address 0x0A), Reference  
Frequency Control  
Bit  
Description  
Set to 01  
6
5
4
3
2
1
0
Set to 0  
Set to 0  
Set to 0  
Set to 0  
Set to 0  
Set to 0  
Set to 0  
7
6
R/2 divider setting1  
0 = bypass R/2 divider (default)  
1 = select R/2 divider  
Reference frequency doubler (R-doubler) enable1  
0 = disable doubler (default)  
1 = enable doubler  
5
[4:0]  
5-bit R-divider setting1  
00000 = divide by 32 (default)  
00001 = divide by 1  
00010 = divide by 2  
Table 21. Register CR23 (Address 0x17), Lock Detector Control 1  
Bit  
Description  
7
Set to 0  
6
Set to 1  
5
Set to 1  
11110 = divide by 30  
11111 = divide by 31  
4
Lock detector enable  
0 = lock detector disabled (default)  
1 = lock detector enabled  
Lock detector up/down count, LDCount0 (see Table 7)  
Lock detector precision  
0 = low, coarse (10 ns)  
1 = high, fine (6 ns)  
Set to 0  
1 Double-buffered. Loaded on a write to Register CR0.  
3
2
1
0
Set to 0  
Rev. B | Page 33 of 48  
 
 
ADRF6755  
Data Sheet  
Table 22. Register CR24 (Address 0x18), Autocalibration  
Table 26. Register CR29 (Address 0x1D), Modulator  
Bit  
Description  
Bit  
Description  
7
Set to 0  
7
Set to 1  
6
Set to 0  
6
Set to 0  
5
Set to 0  
5
Set to 0  
4
Set to 1  
4
Set to 0  
3
Set to 1  
3
Set to 0  
2
Set to 0  
2
Set to 0  
1
Set to 0  
1
Set to 0  
0
Disable autocalibration  
0 = enable autocalibration (default)  
1 = disable autocalibration  
0
Power up modulator  
0 = power down (default)  
1 = power up  
Table 23. Register CR25 (Address 0x19), Autocalibration Timer  
Table 27. Register CR30 (Address 0x1E), Attenuator  
Bit  
Description  
Bit  
Description  
[7:0]  
Autocalibration timer  
7
Set to 0  
6
Set to 0  
[5:0]  
Attenuator A5 to Attenuator A0  
000000 = 0 dB  
000001 = 1 dB  
000010 = 2 dB  
Table 24. Register CR27 (Address 0x1B), LO Monitor Output  
and LO Selection  
Bit  
Description  
7
Set to 0  
6
Set to 0  
011111 = 31 dB  
110000 = 32 dB  
110001 = 33 dB  
111101 = 45 dB  
111110 = 46 dB  
111111 = 47 dB  
5
4
3
2
Set to 0  
Frequency range; set according to Table 6  
Set to 0  
Power up LO monitor output  
0 = power down (default)  
1 = power up  
Monitor output power into 50 Ω  
00 = −24 dBm (default)  
01 = −18 dBm  
[1:0]  
Table 28. Register CR33 (Address 0x21), Revision Code1  
Bit  
Description  
10 = −12 dBm  
11 = −6 dBm  
[7:0]  
Revision code  
1 Read-only register.  
Table 25. Register CR28 (Address 0x1C), LO Selection  
Bit  
Description  
7
Set to 0  
6
Set to 0  
5
Set to 0  
4
Power down RFDIVIDER  
0 = power up (default)  
1 = power down  
Set to 1  
3
[2:0]  
RFDIV1, set according to Table 6  
1 Double-buffered. Loaded on a write to Register CR0.  
Rev. B | Page 34 of 48  
 
 
Data Sheet  
ADRF6755  
SUGGESTED POWER-UP SEQUENCE  
22. Write 0xF0 to Register CR9. With the recommended loop  
filter component values and RSET = 4.7 kΩ, as shown in  
Figure 70, the charge pump current is set to 5 mA for a  
loop bandwidth of 100 kHz.  
23. Write 0x00 to Register CR8. Reserved register.  
24. Write 0x0X to Register CR7. Set according to Equation 2 in  
the Theory of Operation section. Also, set the MUXOUT  
pin to tristate.  
25. Write 0xXX to Register CR6. Set according to Equation 2  
in the Theory of Operation section.  
26. Write to Register CR5. Refer to the Reference Input Path  
section, in particular Equation 1.  
27. Write 0x01 to Register CR4. Reserved register.  
28. Write 0000010X binary to Register CR3. Set according to  
Equation 2 in the Theory of Operation section.  
29. Write 0xXX to Register CR2. Set according to Equation 2  
in the Theory of Operation section.  
30. Write 0xXX to Register CR1. Set according to Equation 2  
in the Theory of Operation section.  
31. Write 0xXX to Register CR0. Set according to Equation 2  
in the Theory of Operation section. Register CR0 must be  
the last register written for all the double-buffered bit  
writes to take effect.  
INITIAL REGISTER WRITE SEQUENCE  
After applying power to the part, perform the initial register write  
sequence that follows. Note that Register CR33, Register CR32, and  
Register CR31 are read-only registers. Also, note that all writable  
registers should be written to on power-up. Refer to the Register  
Map section for more details on all registers.  
1. Write 0x00 to Register CR30. Set the attenuator to 0 dB gain.  
2. Write 0x80 to Register CR29. The modulator is powered  
down. The modulator is powered down by default to ensure  
that no spurious signals can occur on the RF output when  
the PLL is carrying out its first acquisition. The modulator  
should be powered up only when the PLL is locked.  
3. Write 0x0X to Register CR28. RFDIV depends on the value  
of the LO frequency to be used and is set according to  
Table 6. Note that Register CR28, Bit 3, is set to 1.  
4. Write 0xX0 to Register CR27. Bit 4 depends on the LO  
frequency to be used and is set according to Table 6.  
5. Write 0x00 to Register CR26. Reserved register.  
6. Write 0x64 to Register CR25, the autocalibration timer.  
This setting applies for PFD = 40 MHz. For other PFDs,  
refer to Equation 3 in the VCO Autocalibration section.  
7. Write 0x18 to Register CR24. Enable autocalibration.  
8. Write 0x70 to Register CR23. Enable the lock detector and  
choose the recommended lock detect timing. This setting  
applies to PFD = 40 MHz. For other PFDs, refer to the  
Lock Detect (LDET) section in the Program Modes  
section.  
9. Write 0x80 to Register CR22. Reserved register.  
10. Write 0x00 to Register CR21. Reserved register.  
11. Write 0x00 to Register CR20. Reserved register.  
12. Write 0x80 to Register CR19. Reserved register.  
13. Write 0x60 to Register CR18. Reserved register.  
14. Write 0x00 to Register CR17. Reserved register.  
15. Write 0x00 to Register CR16. Reserved register.  
16. Write 0x00 to Register CR15. Reserved register.  
17. Write 0x80 to Register CR14. Stop LO when TXDIS = 1.  
18. Write 0xE8 to Register CR13. This setting applies to PFD =  
40 MHz. For other PFDs, refer to the Lock Detect (LDET)  
32. Write to Register CR27, setting Bit 4 according to Table 6.  
33. Monitor the LDET output or wait 170 μs to ensure that the  
PLL is locked.  
34. Write 0x81 to Register CR29. Power up the modulator. The  
write to Register CR29 does not need to be followed by a write  
to Register CR0 because this register is not double-buffered.  
Example—Changing the LO Frequency  
Following is an example of how to change the LO frequency  
after the initialization sequence. Using an example in which  
the PLL is locked to 2000 MHz, the following conditions apply:  
fPFD = 40 MHz (assumed)  
Divide ratio N = 50; therefore, INT = 50 decimal and  
FRAC = 0  
RFDIVIDER = divide-by-1. See Table 6.  
section in the Program Modes  
section.  
Register CR28[2:0] = 000  
Register CR27[4] = 1  
19. Write 0x18 to Register CR12. Power up the PLL.  
20. Write 0x00 to Register CR11. Reserved register.  
21. Write to Register CR10. Refer to the Reference Input Path  
section, in particular Equation 1.  
The INT registers contain the following values:  
Register CR7 = 0x00 and Register CR6 = 0x32  
The FRAC registers contain the following values:  
Register CR3 = 0x04, Register CR2 = 0x00,  
Register CR1 = 0x00, and Register CR0 = 0x00  
Rev. B | Page 35 of 48  
 
 
 
ADRF6755  
Data Sheet  
To change the LO frequency to 925 MHz,  
The FRAC registers contain the following values:  
Register CR3 = 0x04, Register CR2 = 0x80,  
Register CR1 = 0x00, and Register CR0 = 0x00  
fPFD = 40 MHz (assumed)  
Divide ratio N = 46.25; therefore, INT = 46 decimal and  
FRAC = 8,388,608  
Note that Register CR27 should be the last write in this  
sequence, preceded by CR0. Writing to Register CR0 causes all  
double-buffered registers to be updated, including the INT,  
FRAC, and RFDIV registers, and starts a new PLL acquisition.  
RFDIVIDER = divide-by-2. See Table 6.  
Register CR28[2:0] = 001  
Register CR27[4] = 0  
The INT registers contain the following values:  
Register CR7 = 0x00 and Register CR6 = 0x2E  
Rev. B | Page 36 of 48  
Data Sheet  
ADRF6755  
EVALUATION BOARD  
SPI Interface  
GENERAL DESCRIPTION  
The SPI interface is provided by an additional SPD-S board. This  
must be ordered with the ADRF6755 evaluation board. The system  
demonstration platform (SDP) is a hardware and software platform  
that provides a means to communicate from the PC to Analog  
Devices products and systems that require digital control and/or  
readback (see Figure 71).  
The EVAL -ADRF6755SDZ evaluation board is designed to allow  
the user to evaluate the performance of the ADRF6755. It contains  
the following:  
I/Q modulator with integrated fractional-N PLL and VCO  
Connector to interface to a standard USB interface board  
(SPD-S) that must be ordered with the EVAL -ADRF6755SDZ  
board.  
The SDP-S controller board connects to the PC via USB 2.0 and  
to the ADRF6755 evaluation board via a small footprint, 120-pin  
connector. The SDP-S (serial only interface) is a low cost, small  
form factor, SDP controller board.  
DC biasing and filter circuitry for the baseband inputs  
Low-pass loop filter circuitry  
An 80 MHz reference clock  
Circuitry to monitor the LOMON outputs  
SMA connectors for power supplies and the RF output  
Baseband Inputs  
The pair of I and Q baseband inputs are served by SMA inputs  
(J2 to J5) so that they can be driven directly from an external  
generator or a DAC board, both of which can also provide the  
dc bias required. There is also an option to filter the baseband  
inputs, although filtering may not be required, depending on  
the quality of the baseband source.  
The evaluation board is supplied with the associated driver  
software to allow easy programming of the ADRF6755.  
HARDWARE DESCRIPTION  
For more information, refer to the circuit diagram in Figure 70.  
Power Supplies  
Loop Filter  
A fourth-order loop filter is provided at the output of the charge  
pump and is required to adequately filter noise from the Σ-Δ  
modulator used in the N-divider. With the charge pump current  
set to a value of 5 mA and using the on-chip VCO, the loop  
bandwidth is approximately 100 kHz, and the phase margin is  
55°. C0G capacitors are recommended for use in the loop filter  
because they have low dielectric absorption, which is required  
for fast and accurate settling time. The use of non-C0G capacitors  
may result in a long tail being introduced into the settling time  
transient.  
An external 5 V supply, DUT +5 V (J14), drives both an on-chip  
3.3 V regulator and the quadrature modulator.  
The regulator feeds the VREG1 through VREG6 pins on the  
chip with 3.3 V. These pins power the PLL circuitry.  
The external reference clock generator should be driven by a  
3.3 V supply. This supply should be connected via an SMA  
connector, OSC +V (J15).  
Recommended Decoupling for Supplies  
The external DUT +5 V supply is decoupled initially by a 10 µF  
capacitor and then further by a parallel combination of 100 nF  
and 10 pF capacitors that are placed as close to the DUT as  
possible for good local decoupling. The regulator output should  
be decoupled by a parallel combination of 10 pF and 220 µF  
capacitors. The 220 µF capacitor decouples broadband noise,  
which leads to better phase noise and is recommended for best  
performance. Case Size C 220 µF capacitors are used to minimize  
area. Place a parallel combination of 100 nF and 10 pF capacitors  
on each VREGx pin, as close to the pins as possible. The impedance  
of these capacitors should be low and constant across a broad  
frequency range. Surface-mount multilayered ceramic chip  
(MLCC) Class II capacitors provide very low ESL and ESR, which  
assist in decoupling supply noise effectively. They also provide  
good temperature stability and good aging characteristics.  
Reference Input  
The reference input can be supplied by an 80 MHz Jauch clock  
generator or by an external clock through the use of Connector  
REFIN (J7). The frequency range of the PFD input is from 10 MHz  
to 40 MHz; if the 80 MHz clock generator is used, the on-chip 5-bit  
reference frequency divider or the divide-by-2 divider should be  
used to set the PFD frequency to 40 MHz to optimize phase noise  
performance.  
LOMON Outputs  
These pins are differential LO monitor outputs that provide a  
replica of the internal LO frequency at 1× LO. The single-ended  
power in a 50 Ω load can be programmed to −24 dBm, −18 dBm,  
−12 dBm, or −6 dBm. These open-collector outputs must be  
terminated to 3.3 V. B e caus e both outputs must be terminated  
to 50 Ω, options are provided to terminate to 3.3 V using on-  
board 50 Ω resistors or by series inductors (or a ferrite bead),  
in which case the 50 Ω termination is provided by the measuring  
instrument. If not used, these outputs should be tied to REGOUT.  
Capacitance also changes vs. applied bias voltage. Larger case  
sizes have less capacitance change vs. applied bias voltage and  
have lower ESR but higher ESL. The 0603 size capacitors provide a  
good compromise. X5R and X7R capacitors are examples of  
these types of capacitors and are recommended for decoupling.  
Rev. B | Page 37 of 48  
 
 
 
ADRF6755  
Data Sheet  
CCOMPx Pins  
Lock Detect (LDET)  
The CCOMPx pins are internal compensation nodes that must  
be decoupled to ground with a 100 nF capacitor.  
Lock detect is a CMOS output that indicates the state of the  
PLL. A high level indicates a locked condition, and a low level  
indicates a loss of lock condition.  
MUXOUT  
TXDIS  
MUXOUT is a test output that allows different internal nodes  
to be monitored. It is a CMOS output stage that requires no  
termination.  
This input disables the RF output. It can be driven from an external  
stimulus or simply connected high or low by Jumper J18.  
RF Output (RFOUT)  
RFOUT (J12) is the RF output of the ADRF6755.  
Rev. B | Page 38 of 48  
Data Sheet  
ADRF6755  
0 7 1  
1
Figure 70. Applications Circuit Schematic  
Rev. B | Page 39 of 48  
 
ADRF6755  
Data Sheet  
Figure 71. Applications Circuit Schematic—SDP-S  
Rev. B | Page 40 of 48  
 
Data Sheet  
ADRF6755  
PCB ARTWORK  
Component Placement  
Figure 72. Evaluation Board, Top Side Component Placement  
Figure 73. Evaluation Board, Bottom Side Component Placement  
Rev. B | Page 41 of 48  
 
ADRF6755  
Data Sheet  
PCB Layer Information  
Figure 74. Evaluation Board, Top Side—Layer 1  
Figure 75. Evaluation Board, Bottom Side—Layer 4  
Rev. B | Page 42 of 48  
Data Sheet  
ADRF6755  
Figure 76. Evaluation Board, Ground—Layer 2  
Figure 77. Evaluation Board Power—Layer 3  
Rev. B | Page 43 of 48  
ADRF6755  
Data Sheet  
BILL OF MATERIALS  
Table 29. Bill of Materials  
Qty Reference Designator  
Description  
Manufacturer  
Analog Devices  
Jauch  
Hirose  
AVX  
Part Number  
1
DUT  
ADRF6755, 56-lead 8 mm × 8 mm LFCSP  
Crystal Oscillator, 80 MHz  
Connector, FX8-120S-SV(21)  
Capacitor, 10 µF, 25 V, tantalum, TAJ-C  
Capacitor, 10 pF, 50 V, ceramic, C0G, 0402  
ADRF6755ACPZ  
O 80.0-JO75-B-3.3-2-T1  
FEC 1324660  
FEC 197518  
FEC 8819564  
1
Y2  
1
2
CONN1  
C1, C21  
12  
C4, C6, C8, C10, C12, C14, C16,  
C18, C19, C48, C53, C55  
Murata  
14  
C5, C7, C9, C11, C13, C15, C17,  
C22, C47, C49 to C52, C54  
C20  
C30 to C33  
C26  
C24  
C23, C25  
C38, C39  
C44, C46, C57  
Capacitor, 100 nF, 25 V, X7R, ceramic, 0603  
AVX  
FEC 317287  
FEC 197087  
1
4
1
1
2
2
3
Capacitor, 220 µF, 6.3 V, tantalum, Case Size C AVX  
Capacitor spacing, 0402 (do not install)  
Capacitor, 1.2 nF, 50 V, C0G, ceramic, 0603  
Capacitor, 47 nF, 50 V, C0G, ceramic, 1206  
Capacitor, 560 pF, 50 V, NP0, ceramic, 0603  
Capacitor, 1 nF, 50 V, C0G, ceramic, 0402  
Capacitor, 100 pF, 50 V, C0G, ceramic, 0402  
Kemet  
FEC 1813421  
FEC 8820201  
FEC 1828912  
FEC 8819556  
FEC 8819572  
Murata  
Murata  
Murata  
Murata  
11  
2
J2 to J5, J7, J10 to J12, J14, J15, TXDIS SMA end launch connector  
Johnson/Emerson 142-0701-851  
J18, J21  
Jumper, 3-pin + shunt  
Harwin  
FEC 148533 and  
FEC 150411  
2
2
5
2
1
2
1
2
3
4
3
2
1
1
L1, L2  
L3, L4  
Inductor, 20 nH, 0402, 5%  
TE Connectivity  
Vishay  
Multicomp  
FEC 1265424  
FEC 1653752  
FEC 1357983  
Inductor, 10 µH, 0805, LQM series  
Resistor, 0 Ω, 1/16 W, 1%, 0402  
Resistor, 0402, spacing (do not install)  
Resistor, 4.7 kΩ, 1/10 W, 1%, 0603  
Resistor, 160 Ω, 1/16 W, 1%, 0603  
Resistor, 150 Ω, 1/16 W, 1%, 0603  
Resistor, 0603, spacing (do not install)  
Resistor, 51 Ω, 1/16 W, 5%, 0402  
Resistor, 330 Ω, 1/10 W, 5%, 0805  
Resistor, 100 Ω, 1/10 W, 5%, 0805  
Resistor, 100 kΩ, 1/16 W, 1%, 0603  
LED, red, 0805, 1.8 V, low current  
IC 24LC32A-I/MS EEPROM MSOP-8  
R6 to R9, R36  
R10, R11  
R13  
R12, R16  
R15  
Bourns  
Multicomp  
Multicomp  
FEC 2008358  
FEC 9330658  
FEC 9330593  
R62  
R35, R44, R45  
R48 to R51  
R59 to R61  
R63, R64  
D1  
Bourns  
Vishay  
Vishay  
Multicomp  
Rohm  
FEC 2008358  
FEC 1739223  
FEC 1652907  
FEC 9330402  
FEC 1685056  
FEC 133-4660  
U1  
Microchip  
Rev. B | Page 44 of 48  
 
Data Sheet  
ADRF6755  
OUTLINE DIMENSIONS  
0.30  
0.23  
0.18  
8.10  
8.00 SQ  
7.90  
0.60 MAX  
0.60  
MAX  
PIN 1  
INDICATOR  
43  
42  
56  
1
0.50  
BSC  
PIN 1  
INDICATOR  
7.85  
EXPOSED  
PAD  
6.65  
6.50 SQ  
6.35  
7.75 SQ  
7.65  
29  
28  
14  
15  
0.50  
0.40  
0.30  
0.20 MIN  
BOTTOM VIEW  
6.50 REF  
TOP VIEW  
0.80 MAX  
0.65 TYP  
1.00  
0.85  
0.80  
12° MAX  
FOR PROPER CONNECTION OF  
THE EXPOSED PAD, REFER TO  
THE PIN CONFIGURATION AND  
FUNCTION DESCRIPTIONS  
0.05 MAX  
0.02 NOM  
COPLANARITY  
0.20 REF  
0.08  
SECTION OF THIS DATA SHEET.  
SIDE VIEW  
SEATING  
PLANE  
COMPLIANT TO JEDEC STANDARDS MO-220-VLLD-2  
Figure 78. 56-Lead Lead Frame Chip Scale Package [LFCSP_VQ]  
8 mm × 8 mm Body, Very Thin Quad  
(CP-56-4)  
Dimensions shown in millimeters  
ORDERING GUIDE  
Package  
Option  
Model1, 2  
Temperature Range Package Description  
ADRF6755ACPZ  
ADRF6755ACPZ-R7  
EVAL-ADRF6755SDZ  
EVAL-SDP-CS1Z  
EVAL-SDP-CB1Z  
−40°C to +85°C  
−40°C to +85°C  
56-Lead Lead Frame Chip Scale Package [LFCSP_VQ], Tray  
56-Lead Lead Frame Chip Scale Package [LFCSP_VQ], 7" Tape and Reel  
Evaluation Board  
SDP-S Controller Board; Interface to EVAL-ADRF6755SDZ (also required)  
SDP-B Controller Board; Interface to EVAL-ADRF6755SDZ (alternative solution)  
CP-56-4  
CP-56-4  
1 Z = RoHS Compliant Part.  
2 Choose either EVAL-SDP-CS1Z or EVAL-SDP-CB1Z as EVAL-ADRF6755SDZ interface solution.  
Rev. B | Page 45 of 48  
 
 
 
ADRF6755  
NOTES  
Data Sheet  
Rev. B | Page 46 of 48  
Data Sheet  
NOTES  
ADRF6755  
Rev. B | Page 47 of 48  
ADRF6755  
NOTES  
Data Sheet  
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).  
©2012–2013 Analog Devices, Inc. All rights reserved. Trademarks and  
registered trademarks are the property of their respective owners.  
D10465-0-4/13(B)  
Rev. B | Page 48 of 48  

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