AD9850BRS [ADI]

CMOS, 125 MHz Complete DDS Synthesizer; CMOS , 125 MHz的完整DDS频率合成器
AD9850BRS
型号: AD9850BRS
厂家: ADI    ADI
描述:

CMOS, 125 MHz Complete DDS Synthesizer
CMOS , 125 MHz的完整DDS频率合成器

数据分配系统
文件: 总19页 (文件大小:375K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
CMOS, 125 MHz  
Complete DDS Synthesizer  
a
AD9850  
FUNCTIONAL BLOCK DIAGRAM  
FEATURES  
125 MHz Clock Rate  
+V  
GND  
S
On-Chip High Performance DAC and High Speed  
Comparator  
DAC SFDR > 50 dB @ 40 MHz AOUT  
32-Bit Frequency Tuning Word  
Simplified Control Interface: Parallel Byte or Serial  
Loading Format  
Phase Modulation Capability  
+3.3 V or +5 V Single Supply Operation  
Low Power: 380 mW @ 125 MHz (+5 V)  
Low Power: 155 mW @ 110 MHz (+3.3 V)  
Power-Down Function  
DAC R  
SET  
REF  
HIGH SPEED  
DDS  
CLOCK IN  
10-BIT  
DAC  
ANALOG  
OUT  
MASTER  
RESET  
PHASE  
32-BIT  
TUNING  
WORD  
AND  
ANALOG  
IN  
CONTROL  
WORDS  
FREQUENCY  
UPDATE/  
DATA REGISTER  
RESET  
FREQUENCY/PHASE  
DATA REGISTER  
CLOCK OUT  
CLOCK OUT  
WORD LOAD  
CLOCK  
COMPARATOR  
DATA INPUT REGISTER  
SERIAL  
LOAD  
AD9850  
PARALLEL  
LOAD  
Ultrasmall 28-Lead SSOP Packaging  
1-BIT  
40 LOADS  
8-BITS  
APPLICATIONS  
5 LOADS  
Frequency/Phase–Agile Sine-Wave Synthesis  
Clock Recovery and Locking Circuitry for Digital  
Communications  
FREQUENCY, PHASE, AND CONTROL  
DATA INPUT  
Digitally Controlled ADC Encode Generator  
Agile Local Oscillator Applications  
combination thereof. The AD9850 also contains a high speed  
comparator that can be configured to accept the (externally)  
filtered output of the DAC to generate a low jitter square wave  
output. This facilitates the device’s use as an agile clock gen-  
erator function.  
GENERAL DESCRIPTION  
The AD9850 is a highly integrated device that uses advanced  
DDS technology coupled with an internal high speed, high  
performance, D/A converter and comparator, to form a com-  
plete digitally programmable frequency synthesizer and clock  
generator function. When referenced to an accurate clock  
source, the AD9850 generates a spectrally pure, frequency/  
phase-programmable, analog output sine wave. This sine wave  
can be used directly as a frequency source or converted to a  
square wave for agile-clock generator applications. The AD9850’s  
innovative high speed DDS core provides a 32-bit frequency  
tuning word, which results in an output tuning resolution of  
0.0291 Hz, for a 125 MHz reference clock input. The  
AD9850’s circuit architecture allows the generation of output  
frequencies of up to one-half the reference clock frequency (or  
62.5 MHz), and the output frequency can be digitally changed  
(asynchronously) at a rate of up to 23 million new frequencies  
per second. The device also provides five bits of digitally  
controlled phase modulation, which enables phase shifting of its  
output in increments of 180°, 90°, 45°, 22.5°, 11.25° and any  
The frequency tuning, control, and phase modulation words are  
loaded into the AD9850 via a parallel byte or serial loading  
format. The parallel load format consists of five iterative loads  
of an 8-bit control word (byte). The first byte controls phase  
modulation, power-down enable, and loading format; bytes 2–5  
comprise the 32-bit frequency tuning word. Serial loading is  
accomplished via a 40-bit serial data stream on a single pin. The  
AD9850 Complete-DDS uses advanced CMOS technology to  
provide this breakthrough level of functionality and performance  
on just 155 mW of power dissipation (+3.3 V supply).  
The AD9850 is available in a space saving 28-lead SSOP, sur-  
face mount package. It is specified to operate over the extended  
industrial temperature range of –40°C to +85°C.  
REV. E  
Information furnished by Analog Devices is believed to be accurate and  
reliable. However, no responsibility is assumed by Analog Devices for its  
use, nor for any infringements of patents or other rights of third parties  
which may result from its use. No license is granted by implication or  
otherwise under any patent or patent rights of Analog Devices.  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781/329-4700  
Fax: 781/326-8703  
World Wide Web Site: http://www.analog.com  
© Analog Devices, Inc., 1999  
(V = +5 V ؎ 5% except as noted, RSET = 3.9 k)  
S
AD9850–SPECIFICATIONS  
AD9850BRS  
Typ  
Parameter  
Temp  
Test Level  
Min  
Max  
Units  
CLOCK INPUT CHARACTERISTICS  
Frequency Range  
+5 V Supply  
+3.3 V Supply  
Full  
Full  
IV  
IV  
1
1
125  
110  
MHz  
MHz  
Pulsewidth High/Low  
+5 V Supply  
+3.3 V Supply  
+25°C  
+25°C  
IV  
IV  
3.2  
4.1  
ns  
ns  
DAC OUTPUT CHARACTERISTICS  
Full-Scale Output Current  
RSET = 3.9 kΩ  
+25°C  
+25°C  
+25°C  
Full  
+25°C  
Full  
+25°C  
+25°C  
+25°C  
+25°C  
+25°C  
+25°C  
V
V
I
V
I
V
I
I
V
IV  
IV  
I
10.24  
20.48  
mA  
mA  
% FS  
ppm/°C  
µA  
RSET = 1.95 kΩ  
Gain Error  
Gain Temperature Coefficient  
Output Offset  
Output Offset Temperature Coefficient  
Differential Nonlinearity  
Integral Nonlinearity  
Output Slew Rate (50 , 2 pF Load)  
Output Impedance  
Output Capacitance  
Voltage Compliance  
–10  
50  
+10  
10  
150  
50  
nA/°C  
LSB  
LSB  
V/µs  
kΩ  
0.5  
0.5  
400  
120  
0.75  
1
8
1.5  
pF  
V
Spurious-Free Dynamic Range (SFDR):  
Wideband (Nyquist Bandwidth)  
1 MHz Analog Out  
20 MHz Analog Out  
40 MHz Analog Out  
Narrowband  
+25°C  
+25°C  
+25°C  
IV  
IV  
IV  
63  
50  
46  
72  
58  
54  
dBc  
dBc  
dBc  
40.13579 MHz 50 kHz  
40.13579 MHz 200 kHz  
4.513579 MHz 50 kHz/20.5 MHz CLK  
4.513579 MHz 200 kHz/20.5 MHz CLK  
+25°C  
+25°C  
+25°C  
+25°C  
IV  
IV  
IV  
IV  
80  
77  
84  
84  
dBc  
dBc  
dBc  
dBc  
COMPARATOR INPUT CHARACTERISTICS  
Input Capacitance  
Input Resistance  
Input Current  
Input Voltage Range  
+25°C  
+25°C  
+25°C  
+25°C  
Full  
V
IV  
I
IV  
VI  
3
pF  
kΩ  
µA  
V
500  
–12  
0
+12  
VDD  
30  
Comparator Offset*  
30  
mV  
COMPARATOR OUTPUT CHARACTERISTICS  
Logic “1” Voltage +5 V Supply  
Logic “1” Voltage +3.3 V Supply  
Full  
Full  
Full  
+25°C  
+25°C  
+25°C  
+25°C  
+25°C  
VI  
VI  
VI  
V
V
V
+4.8  
+3.1  
V
V
V
ns  
ns  
ns  
ns  
ps  
Logic “0” Voltage  
+0.4  
Propagation Delay, +5 V Supply (15 pF Load)  
Propagation Delay, +3.3 V Supply (15 pF Load)  
Rise/Fall Time, +5 V Supply (15 pF Load)  
Rise/Fall Time, +3.3 V Supply (15 pF Load)  
Output Jitter (p-p)  
5.5  
7
3
3.5  
80  
V
V
CLOCK OUTPUT CHARACTERISTICS  
Clock Output Duty Cycle (Clk Gen. Config.)  
+25°C  
IV  
50 10  
%
–2–  
REV. E  
AD9850  
AD9850BRS  
Min Typ Max  
Parameter  
Temp  
Test Level  
Units  
CMOS LOGIC INPUTS (Including CLKIN)  
Logic “1” Voltage, +5 V Supply  
Logic “1” Voltage, +3.3 V Supply  
Logic “0” Voltage  
Logic “1” Current  
Logic “0” Current  
+25°C  
+25°C  
+25°C  
+25°C  
+25°C  
+25°C  
I
I
I
I
I
V
3.5  
3.0  
0.4  
12  
12  
3
V
V
V
µA  
µA  
pF  
Input Capacitance  
POWER SUPPLY (AOUT = 1/3 CLKIN)  
+VS Current @:  
62.5 MHz Clock, +3.3 V Supply  
110 MHz Clock, +3.3 V Supply  
62.5 MHz Clock, +5 V Supply  
125 MHz Clock, +5 V Supply  
PDISS @:  
Full  
Full  
Full  
Full  
VI  
VI  
VI  
VI  
30  
47  
44  
76  
48  
60  
64  
96  
mA  
mA  
mA  
mA  
62.5 MHz Clock, +3.3 V Supply  
110 MHz Clock, +3.3 V Supply  
62.5 MHz Clock, +5 V Supply  
125 MHz Clock, +5 V Supply  
PDISS Power-Down Mode  
+5 V Supply  
Full  
Full  
Full  
Full  
VI  
VI  
VI  
VI  
100  
155  
220  
380  
160  
200  
320  
480  
mW  
mW  
mW  
mW  
Full  
Full  
V
V
30  
10  
mW  
mW  
+3.3 V Supply  
NOTES  
*Tested by measuring output duty cycle variation.  
Specifications subject to change without notice.  
(V = +5 V ؎ 5% except as noted, RSET = 3.9 k)  
S
TIMING CHARACTERISTICS*  
AD9850BRS  
Parameter  
Temp  
Test Level  
Min  
Typ Max  
Units  
tDS (Data Setup Time)  
tDH (Data Hold Time)  
Full  
Full  
Full  
Full  
Full  
Full  
Full  
Full  
IV  
IV  
IV  
IV  
IV  
IV  
IV  
IV  
3.5  
3.5  
3.5  
3.5  
7.0  
3.5  
7.0  
7.0  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
tWH (W_CLK min. Pulsewidth High)  
tWL (W_CLK min. Pulsewidth Low)  
tWD (W_CLK Delay After FQ_UD)  
tCD (CLKIN Delay After FQ_UD)  
tFH (FQ_UD High)  
tFL (FQ_UD Low)  
tCF (Output Latency from FQ_UD)  
Frequency Change  
Full  
Full  
Full  
Full  
Full  
Full  
Full  
Full  
+25°C  
IV  
IV  
IV  
IV  
IV  
IV  
IV  
IV  
V
18  
13  
7.0  
3.5  
3.5  
5
CLKIN Cycles  
CLKIN Cycles  
ns  
ns  
Phase Change  
tFD (FQ_UD Min. Delay After W_CLK)  
tRH (CLKIN Delay After RESET Rising Edge)  
tRL (RESET Falling Edge After CLKIN)  
tRS (Minimum RESET Width)  
tOL (RESET Output Latency)  
tRR (Recovery from RESET)  
Wake-Up Time from Power-Down Mode  
ns  
CLKIN Cycles  
CLKIN Cycles  
CLKIN Cycles  
µs  
13  
2
5
NOTES  
*Control functions are asynchronous with CLKIN.  
Specifications subject to change without notice.  
–3–  
REV. E  
AD9850  
ABSOLUTE MAXIMUM RATINGS*  
EXPLANATION OF TEST LEVELS  
Test Level  
Maximum Junction Temperature . . . . . . . . . . . . . . . +165°C  
VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6 V  
Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . –0.7 V to +VS  
Digital Output Continuous Current . . . . . . . . . . . . . . . 5 mA  
DAC Output Current . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA  
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +150°C  
Operating Temperature . . . . . . . . . . . . . . . . . –40°C to +85°C  
Lead Temperature (Soldering 10 sec) . . . . . . . . . . . . +300°C  
SSOP θJA Thermal Impedance . . . . . . . . . . . . . . . . . . 82°C/W  
*Absolute maximum ratings are limiting values, to be applied individually, and  
beyond which the serviceability of the circuit may be impaired. Functional  
operability under any of these conditions is not necessarily implied. Exposure of  
absolute maximum rating conditions for extended periods of time may affect  
device reliability.  
I
III  
IV  
100% Production Tested.  
Sample Tested Only.  
Parameter is guaranteed by design and characterization  
testing.  
V
VI  
Parameter is a typical value only.  
All devices are 100% production tested at +25°C.  
100% production tested at temperature extremes for  
military temperature devices; guaranteed by design and  
characterization testing for industrial devices.  
CAUTION  
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily  
accumulate on the human body and test equipment and can discharge without detection.  
Although the AD9850 features proprietary ESD protection circuitry, permanent damage may  
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD  
precautions are recommended to avoid performance degradation or loss of functionality.  
WARNING!  
ESD SENSITIVE DEVICE  
Application Note: Users are cautioned not to apply digital input signals prior to power-up of this  
device. Doing so may result in a latch-up condition.  
ORDERING GUIDE  
Model  
Temperature Range  
Package Description  
Package Option  
AD9850BRS  
–40°C to +85°C  
Shrink Small Outline (SSOP)  
RS-28  
REV. E  
–4–  
AD9850  
Table I. Lead Function Descriptions  
Pin  
No.  
Mnemonic  
Function  
4–1,  
28–25  
D0–D7  
8-Bit Data Input. This is the 8-bit data port for iteratively loading the 32-bit frequency and 8-bit phase/  
control word. D7 = MSB; D0 = LSB. D7 (Pin 25) also serves as the input pin for the 40-bit serial data word.  
5, 24  
6, 23  
7
DGND  
DVDD  
W_CLK  
FQ_UD  
Digital Ground. These are the ground return leads for the digital circuitry.  
Supply Voltage Leads for digital circuitry.  
Word Load Clock. This clock is used to load the parallel or serial frequency/phase/control words.  
8
Frequency Update. On the rising edge of this clock, the DDS will update to the frequency (or phase)  
loaded in the data input register, it then resets the pointer to Word 0.  
9
CLKIN  
Reference Clock Input. This may be a continuous CMOS-level pulse train or sine input biased at  
1/2 V supply. The rising edge of this clock initiates operation.  
10, 19 AGND  
11, 18 AVDD  
Analog Ground. These leads are the ground return for the analog circuitry (DAC and comparator).  
Supply Voltage for the analog circuitry (DAC and comparator).  
12  
RSET  
This is the DAC’s external RSET connection. This resistor value sets the DAC full-scale output current. For  
normal applications (FS IOUT = 10 mA), the value for RSET is 3.9 kconnected to ground. The RSET/IOUT  
relationship is: IOUT = 32 (1.248 V/RSET).  
13  
14  
15  
16  
17  
QOUTB  
QOUT  
VINN  
Output Complement. This is the comparator’s complement output.  
Output True. This is the comparator’s true output.  
Inverting Voltage Input. This is the comparator’s negative input.  
Noninverting Voltage Input. This is the comparator’s positive input.  
VINP  
DACBL (NC) DAC Baseline. This is the DAC baseline voltage reference; this lead is internally bypassed and should  
normally be considered a “no connect” for optimum performance.  
20  
21  
22  
IOUTB  
IOUT  
The Complementary Analog Output of the DAC.  
Analog Current Output of the DAC.  
RESET  
Reset. This is the master reset function; when set high it clears all registers (except the input register) and  
the DAC output will go to Cosine 0 after additional clock cycles—see Figure 19.  
PIN CONFIGURATIONS  
1
2
D4  
D3  
D2  
28  
27  
D5  
3
D1  
D6  
26  
25  
LSB D0  
DGND  
DVDD  
W CLK  
4
D7 MSB/SERIAL LOAD  
5
24  
23  
DGND  
DVDD  
RESET  
6
AD9850  
7
22  
TOP VIEW  
8
21 IOUT  
FQ UD  
CLKIN  
AGND  
AVDD  
(Not to Scale)  
20  
9
IOUTB  
10  
11  
12  
13  
14  
AGND  
19  
18  
AVDD  
R
DACBL (NC)  
17  
16  
SET  
QOUTB  
QOUT  
VINP  
VINN  
15  
NC = NO CONNECT  
REV. E  
–5–  
AD9850Typical Performance Characteristics  
Spectrum  
CH1  
S
–8.6dBm  
76.642 dB  
S
Spectrum  
AD9850  
10dBm  
CLOCK 125MHz  
59.925 dB  
Fxd  
10dB/REF  
CH1  
10dB/REF  
CLOCK 125MHz  
Fxd  
AD9850  
0
0
RBW # 100Hz  
START 0Hz  
VBW 100Hz ATN # 30dB SWP 762 sec  
STOP 62.5MHz  
RBW # 300Hz  
START 0Hz  
VBW 300Hz ATN # 30dB SWP 182.6 sec  
STOP 62.5MHz  
Figure 1. SFDR, CLKIN = 125 MHz/fOUT = 1 MHz  
Figure 4. SFDR, CLKIN = 125 MHz/fOUT = 20 MHz  
Spectrum  
AD9850  
CH1  
S
0dBm  
85.401 dB  
12dB/REF  
S
Spectrum  
AD9850  
10dBm  
CLOCK 125MHz  
54.818 dB  
Fxd  
CH1  
10dB/REF  
23 kHz  
Mkr  
0
0
RBW # 3Hz  
CENTER 4.513579MHz  
VBW 3Hz  
ATN # 20dB SWP 399.5 sec  
SPAN 400kHz  
RBW # 300Hz  
START 0Hz  
VBW 300Hz ATN # 30dB SWP 182.6 sec  
STOP 62.5MHz  
Figure 5. SFDR, CLKIN = 20.5 MHz/fOUT = 4.5 MHz  
Figure 2. SFDR, CLKIN = 125 MHz/fOUT = 41 MHz  
Tek Run: 100GS/s ET Sample  
105  
PN.3RD  
110  
: 300ps  
@: 25.26ns  
115  
120  
125  
130  
135  
140  
145  
150  
155  
1
100  
1k  
10k  
100k  
Ch 1 500mV  
M 20.0ns Ch 1  
1.58V  
OFFSET FROM 5MHz CARRIER Hz  
D 500ps Runs After  
Figure 3. Typical Comparator Output Jitter, AD9850  
Configured as Clock Generator w/42 MHz LP Filter  
(40 MHz AOUT/125 MHz CLKIN)  
Figure 6. Output Residual Phase Noise (5 MHz AOUT  
125 MHz CLKIN)  
/
REV. E  
6–  
AD9850  
Tek Run: 50.0GS/s ET Average  
Tek Run: 50.0GS/s ET Average  
Ch 1 Rise  
2.870ns  
Ch 1 Fall  
3.202ns  
1
1
Ch1 1.00V  
M 1.00ns Ch 1  
1.74V  
Ch1 1.00V  
M 1.00ns Ch 1  
1.74V  
Figure 7. Comparator Output Rise Time  
(5 V Supply/15 pF Load)  
Figure 10. Comparator Output Fall Time  
(5 V Supply/15 pF Load)  
90  
80  
70  
60  
50  
40  
30  
20  
10  
68  
fOUT = 1/3 OF CLKIN  
66  
64  
62  
60  
58  
V
= 5V  
CC  
V
= 3.3V  
CC  
V
= 5V  
56  
54  
52  
CC  
V
= 3.3V  
80  
CC  
0
20  
40  
60  
80  
100  
120  
140  
0
20  
40  
60  
100  
120  
140  
CLOCK FREQUENCY MHz  
CLKIN MHz  
Figure 11. Supply Current vs. CLKIN Frequency  
(AOUT = 1/3 of CLKIN)  
Figure 8. SFDR vs. CLKIN Frequency  
(AOUT = 1/3 of CLKIN)  
75  
90  
80  
fOUT = 1MHz  
70  
V
= 5V  
CC  
65  
70  
60  
50  
40  
30  
60  
fOUT = 20MHz  
55  
V
= 3.3V  
CC  
fOUT = 40MHz  
50  
45  
5
10  
DAC I  
15  
mA  
20  
0
10  
20  
FREQUENCY OUT MHz  
30  
40  
OUT  
Figure 9. Supply Current vs. AOUT Frequency  
(CLKIN = 125/110 MHz for 5 V/3.3 V Plot)  
Figure 12. SFDR vs. DAC IOUT (AOUT = 1/3 of CLKIN)  
REV. E  
7–  
AD9850  
IF  
FREQUENCY  
IN  
RF  
5-POLE ELLIPTICAL  
42MHz LOW-PASS  
200IMPEDANCE  
FILTER  
GND  
FREQUENCY  
OUT  
+V  
S
LOW-PASS  
FILTER  
IOUT  
FILTER  
200⍀  
100k⍀  
100k⍀  
8-b 
؋
 5 PARALLEL DATA,  
OR 1-b 
؋
 40 SERIAL DATA,  
RESET, AND 2  
125MHz  
DATA  
BUS  
AD9850  
TUNING  
WORD  
470pF  
PROCESSOR  
COMPLETE-DDS  
CLOCK LINES  
REFERENCE  
100⍀  
IOUTB  
AD9850  
a. Frequency/PhaseAgile Local Oscillator  
VINN  
XTAL  
OSC  
CLK  
VINP  
QOUT  
200⍀  
RF  
CMOS  
CLOCK  
125MHz  
QOUTB  
FREQUENCY  
OUT  
VCO  
AD9850  
COMPLETE-  
DDS  
OUTPUTS  
FILTER  
PHASE  
LOOP  
COMPARATOR FILTER  
RSET  
COMP  
TRUE  
REFERENCE  
CLOCK  
DIVIDE-BY-N  
TUNING  
WORD  
Figure 13. Basic AD9850 Clock Generator Application  
with Low-Pass Filter  
b. Frequency/PhaseAgile Reference for PLL  
REF  
I
8
8
Rx  
RF  
FREQUENCY  
FREQUENCY  
I/Q MIXER  
AND  
LOW-PASS  
FILTER  
BASEBAND  
DIGITAL  
DATA  
AD9059  
DUAL 8-BIT  
ADC  
DIGITAL  
DEMODULATOR  
Rx  
IF IN  
OUT  
Q
PHASE  
LOOP  
FILTER  
VCO  
COMPARATOR  
OUT  
PROGRAMMABLE  
DIVIDE-BY-N”  
FUNCTION  
AGC  
VCA  
FILTER  
ADC CLOCK  
FREQUENCY  
ADC ENCODE  
LOCKED TO Tx CHIP/  
SYMBOL PN RATE  
AD9850  
COMPLETE-  
DDS  
125MHz  
AD9850  
32  
CLOCK  
GENERATOR  
TUNING WORD  
CHIP/SYMBOL/PN  
RATE DATA  
REFERENCE  
CLOCK  
c. Digitally-Programmable Divide-by-NFunction in PLL  
Figure 14. AD9850 Clock Generator Application in a  
Spread-Spectrum Receiver  
Figure 15. AD9850 Complete-DDS Synthesizer in  
Frequency Up-Conversion Applications  
THEORY OF OPERATION AND APPLICATION  
The AD9850 uses direct digital synthesis (DDS) technology, in  
the form of a numerically controlled oscillator, to generate a  
frequency/phase-agile sine wave. The digital sine wave is con-  
verted to analog form via an internal 10-bit high speed D/A  
converter, and an onboard high speed comparator is provided to  
translate the analog sine wave into a low jitter TTL/CMOS-  
compatible output square wave. DDS technology is an innova-  
tive circuit architecture that allows fast and precise manipulation  
of its output frequency under full digital control. DDS also  
enables very high resolution in the incremental selection of  
output frequency; the AD9850 allows an output frequency  
resolution of 0.0291 Hz with a 125 MHz reference clock ap-  
plied. The AD9850’s output waveform is phase-continuous  
when changed.  
receives a clock pulse. When the counter overflows it wraps  
around, making the phase accumulator’s output contiguous.  
The frequency tuning word sets the modulus of the counter that  
effectively determines the size of the increment (Phase) that  
gets added to the value in the phase accumulator on the next  
clock pulse. The larger the added increment, the faster the ac-  
cumulator overflows, which results in a higher output fre-  
quency. The AD9850 uses an innovative and proprietary  
algorithm that mathematically converts the 14-bit truncated  
value of the phase accumulator to the appropriate COS value.  
This unique algorithm uses a much reduced ROM look-up table  
and DSP techniques to perform this function, which contributes  
to the small size and low power dissipation of the AD9850. The  
relationship of the output frequency, reference clock, and tuning  
word of the AD9850 is determined by the formula:  
The basic functional block diagram and signal flow of the  
AD9850 configured as a clock generator is shown in Figure 16.  
f
OUT = (Phase × CLKIN)/232  
where: Phase = value of 32-bit tuning word  
CLKIN = input reference clock frequency in MHz  
fOUT = frequency of the output signal in MHz  
The DDS circuitry is basically a digital frequency divider function  
whose incremental resolution is determined by the frequency of  
the reference clock divided by the 2N number of bits in the  
tuning word. The phase accumulator is a variable-modulus  
counter that increments the number stored in it each time it  
The digital sine wave output of the DDS block drives the inter-  
nal high speed 10-bit D/A converter that reconstructs the sine  
REV. E  
8–  
AD9850  
REF  
CLOCK  
DDS CIRCUITRY  
AMPLITUDE/COS  
CONV.  
ALGORITHM  
N
PHASE  
ACCUMULATOR  
D/A  
CONVERTER  
CLK  
OUT  
LP  
COMPARATOR  
TUNING WORD SPECIFIES  
OUTPUT FREQUENCY  
AS A FRACTION OF REF  
CLOCK FREQUENCY  
COS (x)  
IN DIGITAL DOMAIN  
Figure 16. Basic DDS Block Diagram and Signal Flow of AD9850  
The reference clock frequency of the AD9850 has a minimum  
limitation of 1 MHz. The device has internal circuitry that  
senses when the minimum clock rate threshold has been exceeded  
and automatically places itself in the power-down mode. When  
in this state, if the clock frequency again exceeds the threshold,  
the device resumes normal operation. This shutdown mode  
prevents excessive current leakage in the dynamic registers of  
the device.  
wave in analog form. This DAC has been optimized for dynamic  
performance and low glitch energy as manifested in the low  
jitter performance of the AD9850. Since the output of the  
AD9850 is a sampled signal, its output spectrum follows the  
Nyquist sampling theorem. Specifically, its output spectrum  
contains the fundamental plus aliased signals (images) that  
occur at multiples of the Reference Clock Frequency the  
selected output frequency. A graphical representation of the  
sampled spectrum, with aliased images, is shown in Figure 17.  
The D/A converter output and comparator inputs are available  
as differential signals that can be flexibly configured in any  
manner desired to achieve the objectives of the end-system. The  
typical application of the AD9850 is with single-ended output/  
input analog signals, a single low-pass filter, and generating the  
comparator reference midpoint from the differential DAC out-  
put as shown in Figure 13.  
f
OUT  
sin(x)/x ENVELOPE  
x=(pi)fo/fc  
fcfo  
fc+fo  
2fcfo  
fc  
2fc+fo  
3fcfo  
Programming the AD9850  
The AD9850 contains a 40-bit register that is used to program the  
32-bit frequency control word, the 5-bit phase modulation word  
and the power-down function. This register can be loaded in a  
parallel or serial mode.  
120MHz  
180MHz  
3RD IMAGE  
220MHz  
4TH IMAGE  
280MHz  
5TH IMAGE  
20MHz  
80MHz  
2ND IMAGE  
FUNDAMENTAL 1ST IMAGE  
100MHz  
REFERENCE CLOCK  
FREQUENCY  
In the parallel load mode, the register is loaded via an 8-bit bus;  
the full 40-bit word requires five iterations of the 8-bit word.  
The W_CLK and FQ_UD signals are used to address and load  
the registers. The rising edge of FQ_UD loads the (up to) 40-bit  
control data word into the device and resets the address pointer  
to the first register. Subsequent W_CLK rising edges load the  
8-bit data on words [7:0] and move the pointer to the next  
register. After five loads, W_CLK edges are ignored until either  
a reset or an FQ_UD rising edge resets the address pointer to  
the first register.  
Figure 17. Output Spectrum of a Sampled Signal  
In this example, the reference clock is 100 MHz and the output  
frequency is set to 20 MHz. As can be seen, the aliased images  
are very prominent and of a relatively high energy level as deter-  
mined by the sin(x)/x roll-off of the quantized D/A converter  
output. In fact, depending on the fo/Ref Clk relationship, the  
first aliased image can be on the order of –3 dB below the fun-  
damental. A low-pass filter is generally placed between the out-  
put of the D/A converter and the input of the comparator to  
further suppress the effects of aliased images. Obviously, con-  
sideration must be given to the relationship of the selected  
output frequency and the Reference Clock frequency to avoid  
unwanted (and unexpected) output anomalies.  
In serial load mode, subsequent rising edges of W_CLK shift  
the 1-bit data on Lead 25 (D7) through the 40 bits of program-  
ming information. After 40 bits are shifted through, an FQ_UD  
pulse is required to update the output frequency (or phase).  
The function assignments of the data and control words are  
shown in Table III; the detailed timing sequence for updating  
the output frequency and/or phase, resetting the device, and  
powering-up/down, are shown in the timing diagrams of Figures  
18–24.  
A good rule-of-thumb for applying the AD9850 as a clock  
generator is to limit the selected output frequency to <33% of  
Reference Clock frequency, thereby avoiding generating aliased  
signals that fall within, or close to, the output band of interest  
(generally dc-selected output frequency). This practice will ease  
the complexity (and cost) of the external filter requirement for  
the clock generator application.  
Note: There are specific control codes, used for factory test  
purposes, that render the AD9850 temporarily inoperable. The  
user must take deliberate precaution to avoid inputting the  
codes listed in Table II.  
REV. E  
9–  
AD9850  
Table II. Factory-Reserved Internal Test Control Codes  
Loading Format  
Factory-Reserved Codes  
Parallel  
1) W0 = XXXXXX10  
2) W0 = XXXXXX01  
Serial  
1) W32 = 1; W33 = 0  
2) W32 = 0; W33 = 1  
3) W32 = 1; W33 = 1  
tCD  
W0*  
tDH  
W1  
W2  
W3  
W4  
DATA  
tDS  
tWH  
tWL  
W CLK  
tFD  
tFL  
tFH  
FQ UD  
REF CLK  
tCF  
VALID DATA  
COS OUT  
OLD FREQ (PHASE)  
NEW FREQ (PHASE)  
*OUTPUT UPDATE CAN OCCUR AFTER ANY WORD LOAD  
AND IS ASYNCHRONOUS WITH THE REFERENCE CLOCK  
SYMBOL DEFINITION  
MIN  
tDS  
tDH  
tWH  
tWL  
tCD  
tFH  
tFL  
DATA SETUP TIME  
3.5ns  
3.5ns  
3.5ns  
3.5ns  
3.5ns  
7.0ns  
7.0ns  
7.0ns  
DATA HOLD TIME  
W CLK HIGH  
W CLK LOW  
CLK DELAY AFTER FQ_UD  
FQ UD HIGH  
FQ UD LOW  
tFD  
tCF  
FQ UD DELAY AFTER W CLK  
OUTPUT LATENCY FROM FQ UD  
FREQUENCY CHANGE 18 CLOCK CYCLES  
PHASE CHANGE 13 CLOCK CYCLES  
Figure 18. Parallel-Load Frequency/Phase Update Timing Sequence  
Table III. 8-Bit Parallel-Load Data/Control Word Functional Assignment  
Word  
data[7]  
data[6]  
data[5]  
data[4]  
data[3]  
data[2]  
data[1]  
data[0]  
W0  
Phase-b4  
(MSB)  
Phase-b3  
Phase-b2  
Phase-b1  
Phase-b0  
(LSB)  
Power-Down  
Control  
Control  
W1  
Freq-b31  
(MSB)  
Freq-b30  
Freq-b29  
Freq-b28  
Freq-b27  
Freq-b26  
Freq-b25  
Freq-b24  
W2  
W3  
W4  
Freq-b23  
Freq-b15  
Freq-b7  
Freq-b22  
Freq-b14  
Freq-b6  
Freq-b21  
Freq-b13  
Freq-b5  
Freq-b20  
Freq-b12  
Freq-b4  
Freq-b19  
Freq-b11  
Freq-b3  
Freq-b18  
Freq-b10  
Freq-b2  
Freq-b17  
Freq-b9  
Freq-b1  
Freq-b16  
Freq-b8  
Freq-b0  
(LSB)  
REV. E  
10–  
AD9850  
REF CLK  
RESET  
tRL  
tRH  
tRR  
tRS  
tOL  
COS (0)  
COS OUT  
SYMBOL DEFINITION  
MIN SPEC  
tRH  
tRL  
tRR  
tRS  
tOL  
CLK DELAY AFTER RESET RISING EDGE  
RESET FALLING EDGE AFTER CLK  
RECOVERY FROM RESET  
3.5ns  
3.5ns  
2 CLK CYCLES  
5 CLK CYCLES  
13 CLK CYCLES  
MINIMUM RESET WIDTH  
RESET OUTPUT LATENCY  
RESULTS OF RESET:  
FREQUENCY/PHASE REGISTER SET TO 0  
ADDRESS POINTER RESET TO W0  
POWER-DOWN BIT RESET TO 0”  
DATA INPUT REGISTER UNEFFECTED  
Figure 19. Master Reset Timing Sequence  
XXXXX100  
DATA (W0)  
W CLK  
FQ UD  
REF CLK  
DAC STROBE  
INTERNAL CLOCKS DISABLED  
Figure 20. Parallel-Load Power-Down Sequence/Internal Operation  
DATA (W0)  
W CLK  
XXXXX000  
FQ UD  
REF CLK  
INTERNAL CLOCKS ENABLED  
Figure 21. Parallel-Load Power-Up Sequence/Internal Operation  
REV. E  
11–  
AD9850  
DATA (W0)  
(PARALLEL)  
XXXXX011  
DATA (SERIAL)  
REQUIRED TO RESET CONTROL REGISTERS  
W32 = 0  
W33 = 0  
W34 = 0  
NOTE: AT LEAST FIRST 8 BITS OF 40-BIT SERIAL LOAD WORD  
ARE REQUIRED TO SHIFT IN REQUIRED W32W34 DATA  
W CLK  
FQ UD  
ENABLE SERIAL MODE  
RESET CONTROL WORDS  
NOTE: FOR DEVICE START-UP IN SERIAL MODE, HARD-WIRE LEAD 2 AT 0, LEAD 3 AT 1, AND LEAD 4 AT 1”  
(SEE FIGURE 23).  
Figure 22. Serial-Load Enable Sequence  
2
3
AD9850BRS  
+V  
SUPPLY  
4
Figure 23. Leads 24 Connection for Default Serial-Mode Operation  
W0  
W1  
W2  
W3  
W39  
DATA –  
FQ UD  
W CLK  
40 W CLK CYCLES  
Figure 24. Serial-Load Frequency/Phase Update Sequence  
Table IV. 40-Bit Serial-Load Word Function Assignment  
W0  
Freq-b0 (LSB)  
Freq-b1  
W14  
W15  
W16  
W17  
W18  
W19  
W20  
W21  
W22  
W23  
W24  
W25  
W26  
W27  
Freq-b14  
Freq-b15  
Freq-b16  
Freq-b17  
Freq-b18  
Freq-b19  
Freq-b20  
Freq-b21  
Freq-b22  
Freq-b23  
Freq-b24  
Freq-b25  
Freq-b26  
Freq-b27  
W28  
W29  
W30  
W31  
W32  
W33  
W34  
W35  
W36  
W37  
W38  
W39  
Freq-b28  
W1  
Freq-b29  
W2  
Freq-b2  
Freq-b30  
W3  
Freq-b3  
Freq-b31 (MSB)  
Control  
W4  
Freq-b4  
W5  
Freq-b5  
Control  
W6  
Freq-b6  
Power-Down  
Phase-b0 (LSB)  
Phase-b1  
W7  
Freq-b7  
W8  
Freq-b8  
W9  
Freq-b9  
Phase-b2  
W10  
W11  
W12  
W13  
Freq-b10  
Freq-b11  
Freq-b12  
Freq-b13  
Phase-b3  
Phase-b4 (MSB)  
REV. E  
12–  
AD9850  
W32=0  
W33=0  
W34=1  
W35=X  
W36=X  
W37=X  
W38=X  
W39=X  
DATA (7) –  
FQ UD  
W CLK  
Figure 25. Serial-Load Power-Down Sequence  
V
V
V
V
CC  
CC  
CC  
CC  
QOUT/  
QOUTB  
DIGITAL  
IN  
VINP/  
VINN  
IOUT IOUTB  
DAC Output  
Comparator Output  
Comparator Input  
Digital Inputs  
Figure 26. AD9850 I/O Equivalent Circuits  
PCB LAYOUT INFORMATION  
Evaluation Boards  
The AD9850/CGPCB and AD9850/FSPCB evaluation boards  
(Figures 27–30) represent typical implementations of the  
AD9850 and exemplify the use of high frequency/high resolu-  
tion design and layout practices. The printed circuit board that  
contains the AD9850 should be a multilayer board that allows  
dedicated power and ground planes. The power and ground  
planes should be free of etched traces that cause discontinuities  
in the planes. It is recommended that the top layer of the multi-  
layer board also contain interspatial ground plane, which makes  
ground available for surface-mount devices. If separate analog  
and digital system ground planes exist, they should be con-  
nected together at the AD9850 for optimum results.  
Two versions of evaluation boards are available for the AD9850,  
which facilitate the implementation of the device for bench-  
top analysis, and serve as a reference for PCB layout. The  
AD9850/FSPCB is intended for applications where the device  
will primarily be used as frequency synthesizer. This version  
facilitates connection of the AD9850’s internal D/A converter  
output to a 50 spectrum analyzer input; the internal com-  
parator on the AD9850 DUT is not enabled (see Figure 28 for  
electrical schematic of AD9850/FSPCB). The AD9850/CGPCB  
is intended for applications using the device in the clock genera-  
tor mode. It connects the AD9850’s DAC output to the internal  
comparator input via a single-ended, 42 MHz low-pass, 5-  
pole Elliptical filter. This model facilitates the access of the  
AD9850’s comparator output for evaluation of the device as a  
frequency- and phase-agile clock source (see Figure 29 for  
electrical schematic of AD9850/CGPCB).  
Avoid running digital lines under the device as these will couple  
noise onto the die. The power supply lines to the AD9850  
should use as large a track as possible to provide a low-impedance  
path and reduce the effects of glitches on the power supply line.  
Fast switching signals like clocks should be shielded with  
ground to avoid radiating noise to other sections of the board.  
Avoid crossover of digital and analog signal paths. Traces on  
opposite sides of the board should run at right angles to each  
other. This will reduce the effects of feedthrough through the  
circuit board. Use microstrip techniques where possible.  
Both versions of the AD9850 evaluation boards are designed to  
interface to the parallel printer port of a PC. The operating  
software runs under Microsoft® Windows and provides a user-  
friendly and intuitive format for controlling the functionality  
and observing the performance of the device. The 3.5" floppy  
provided with the evaluation board contains an executable file  
that loads and displays the AD9850 function-selection screen.  
The evaluation board may be operated with +3.3 V or +5 V  
supplies. The evaluation boards are configured at the factory for  
an external reference clock input; if the onboard crystal clock  
source is used, remove R2.  
Good decoupling is also an important consideration. The analog  
(AVDD) and digital (DVDD) supplies to the AD9850 are  
independent and separately pinned out to minimize coupling  
between analog and digital sections of the device. All analog  
and digital supplies should be decoupled to AGND and DGND,  
respectively, with high quality ceramic capacitors. To achieve  
best performance from the decoupling capacitors, they should  
be placed as close as possible to the device, ideally right up  
against the device. In systems where a common supply is used to  
drive both the AVDD and DVDD supplies of the AD9850, it is  
recommended that the system’s AVDD supply be used.  
Analog Devices, Inc., applications engineering support is avail-  
able to answer additional questions on grounding and PCB  
layout. Call 1-800-ANALOGD.  
All trademarks are the property of their respective holders.  
REV. E  
13–  
AD9850  
AD9850 Evaluation Board Instructions  
Required hardware/software:  
Locate the “CLOCK” box and place the cursor in the frequency  
box. Type in the clock frequency (in MHz) that you will be  
applying to the AD9850. Click the LOAD button or press enter  
on the keyboard.  
IBM compatible computer operating in a Windows environment  
Printer port, 3.5" floppy drive and Centronics compatible  
printer cable.  
XTAL clock or signal generator—if using a signal generator, dc  
offset the signal to one-half the supply voltage and apply at  
least 3 V p-p signal across the 50 (R2) input resistor.  
Remove R2 for high Z clock input.  
AD9850 evaluation board software disk and AD9850/FSPCB or  
AD9850/CGPCB evaluation board.  
+5 V voltage supply  
Move the cursor to the OUTPUT FREQUENCY box and type in  
the desired output frequency (in MHz). Click the “LOAD” button  
or press the enter key. The BUS MONITOR section of the  
control panel will show the 32-bit word that was loaded into the  
AD9850. Upon completion of this step, the AD9850 output  
should be active and outputting your frequency information.  
Changing the output phase is accomplished by clicking on the  
“down arrow” in the OUTPUT PHASE DELAY box to make  
a selection and then clicking the LOAD button.  
Setup:  
Copy the contents of the AD9850 disk onto your hard drive  
(there are three files).  
Connect the printer cable from computer to the AD9850  
evaluation board.  
Apply power to AD9850 evaluation board. The AD9850 is  
powered separately from the connector marked “DUT +V.”  
The AD9850 may be powered with 3.3 V to +5 V.  
Connect external 50 ohm clock or remove R2 and apply a high  
Z input clock such as a crystal “can” oscillator.  
Locate the file called 9850REV2.EXE and execute that program.  
Monitor should display a “control panel” to allow operation of  
the AD9850 evaluation board.  
Other operational modes (Frequency Sweeping, Sleep, Serial  
Input) are available to the user via keyboard/mouse control.  
The AD9850/FSPCB provides access into and out of the on-chip  
comparator via test point pairs (each pair has an active input and a  
ground connection). The two active inputs are labeled TP1 and  
TP2. The unmarked hole next to each labeled test point is a  
ground connection. The two active outputs are labeled TP5 and  
TP6. Unmarked ground connections are adjacent to each of these  
test points.  
The AD9850/CGPCB provides BNC inputs and outputs associ-  
ated with the on-chip comparator and the onboard, 5th order,  
200 ohm input/output Z, elliptic 45 MHz low-pass filter. Jumper-  
ing (soldering a wire) E1 to E2, E3 to E4, and E5 to E6 connects  
the onboard filter and the midpoint switching voltage to the  
comparator. Users may elect to insert their own filter and com-  
parator threshold voltage by removing the jumpers and inserting  
a filter between J7 and J6 and then providing a threshold voltage  
at E1.  
Operation:  
On the control panel, locate the box called “COMPUTER I/O.”  
Point to and click the selection marked LPT1 and then point to  
the “TEST” box and click. A message will appear telling you if  
your choice of output ports is correct. Choose other ports as  
necessary to achieve a correct setting. If you have trouble getting  
your computer to recognize any printer port, try the following:  
connect three 2K pull-up resistors from Pins 9, 8 and 7 of U3 to  
+5 V. This will assist “weak” printer port outputs in driving the  
heavy capacitance load of the printer cable. If troubles persist,  
try a different printer cable.  
If you choose to use the XTAL socket to supply the clock to the  
AD9850, you must remove R2 (a 50 ohm chip resistor). The  
crystal oscillator must be either TTL or CMOS (preferably)  
compatible.  
Locate the “MASTER RESET” button with the mouse and  
click it. This will reset the AD9850 to 0 Hz, 0 degrees phase.  
The output should be a dc voltage equal to the full-scale output  
of the AD9850.  
REV. E  
14–  
AD9850  
C36CRPX  
J1  
U2  
H1  
#6  
H2  
#6  
H3  
#6  
H4  
#6  
1
J2  
J3  
J4  
74HCT574  
RRESET  
+V  
12  
13  
14  
15  
16  
17  
18  
19  
2
9
8
7
6
5
4
3
2
MOUNTING  
D0  
D1  
D2  
D3  
D4  
D5  
D6  
D7  
8D  
7D  
6D  
5D  
4D  
3D  
2D  
1D  
8Q  
7Q  
6Q  
5Q  
4Q  
3Q  
2Q  
1Q  
D3  
D2  
1
2
28  
27  
26  
25  
D3  
D4  
D5  
D6  
D7  
D4  
D5  
D6  
D7  
BANANA  
JACKS  
+5V  
GND  
3
HOLES  
D2  
4
U1  
D1  
3
D1  
5
AD9850  
D0  
GND  
+V  
4
D0  
6
J6  
5
DGND  
DVDD  
W CLK  
FQ UD  
DGND 24 GND  
DVDD 23 +V  
DAC OUT  
TO 50  
7
6
R4  
50⍀  
8
WCLK  
FQUD  
CLKIN  
GND  
+V  
7
RESET 22 RESET  
IOUT 21  
9
8
R5  
25⍀  
10  
11  
12  
13  
14  
15  
16  
CLK  
OE  
9
20  
19  
18  
17  
16  
15  
IOUTB  
AGND  
AVDD  
DACBL  
VINP  
CLKIN  
AGND  
AVDD  
11  
1
10  
11  
12  
GND  
STROBE  
R1  
3.9k⍀  
+V  
10mA  
RSET  
FFQUD  
R
SET  
13 QOUT  
TP1  
TP5  
TP2  
TP3  
TP4  
14 QOUTB  
VINN  
COMPARATOR  
INPUTS  
GND  
GND  
TP6  
TP7  
TP8  
17  
P
COMPARATOR  
OUTPUTS  
GND  
GND  
18  
O
R
T
U3  
74HCT574  
19  
R6  
1k⍀  
20  
12  
9
+V  
1
J5  
RRESET  
WWCLK  
FFQUD  
8D  
7D  
6D  
5D  
4D  
3D  
2D  
8Q  
7Q  
6Q  
5Q  
4Q  
3Q  
2Q  
1Q  
RESET  
21  
13  
8
7
6
5
4
3
2
R7  
1k⍀  
CLKIN  
WCLK  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
14  
R2  
50⍀  
FQUD  
REMOVE  
GND  
15  
WHEN  
CHECK  
RRESET  
USING Y1  
16  
17  
18  
19  
+5V  
14  
VCC  
8
XTAL  
OSC  
OUT  
1D  
Y1  
GND  
7
CLK  
OE  
+5V  
11  
1
R10  
2.2k⍀  
R9  
2.2k⍀  
R8  
2.2k⍀  
R3  
2.2k⍀  
STROBE  
WWCLK  
CHECK  
RRESET FFQUD WWCLK STROBE  
+V  
+5V  
+5V  
+V  
C4  
0.1F  
C8  
0.1F  
C2  
0.1F  
C3  
0.1F  
C5  
0.1F  
C10  
0.1F  
C9  
0.1F  
C6  
10F  
C7  
10F  
STROBE  
Figure 27. AD9850/FSPCB Electrical Schematic  
COMPONENT LIST  
Integrated Circuits  
U1  
AD9850BRS (28-Lead SSOP)  
U2, U3  
74HCT574 H-CMOS Octal Flip-Flop  
Capacitors  
C2–C5, C8–C10  
C6, C7  
0.1 µF Ceramic Chip Capacitor  
10 µF Tantalum Chip Capacitor  
Resistors  
R1  
R2, R4  
R3, R8, R9, R10  
R5  
3.9 kResistor  
50 Resistor  
2.2 kResistor  
25 Resistor  
1 kResistor  
R6, R7  
Connectors  
J1  
J2, J3, J4  
J5, J6  
36-Pin D Connector  
Banana Jack  
BNC Connector  
REV. E  
15–  
AD9850  
c. AD9850/FSPCB Power Plane  
a. AD9850/FSPCB Top Layer  
d. AD9850/FSPCB Bottom Layer  
b. AD9850/FSPCB Ground Plane  
Figure 28. AD9850/FSPCB Evaluation Board Layout  
REV. E  
16–  
AD9850  
C36CRPX  
J1  
J2  
J3  
+V  
H1 H2 H3 H4  
#6 #6 #6 #6  
U2  
BANANA  
JACKS  
+5V  
1
74HCT574  
RRESET  
MOUNTING  
HOLES  
J4  
9
8
7
6
5
4
3
2
12  
13  
14  
15  
16  
17  
18  
19  
2
200Z  
GND  
8Q  
7Q  
6Q  
5Q  
4Q  
3Q  
8D  
7D  
6D  
5D  
4D  
3D  
2D  
D0  
D1  
D2  
D3  
D4  
D5  
D6  
D7  
42MHz ELLIPTIC  
3
LOW PASS FILTER  
4
L2  
L1  
1
2
3
4
5
6
7
8
9
D3  
D2  
D1  
28  
27  
26  
25  
D3  
D4  
D5  
D4  
D5  
D6  
D7  
1008CS  
680nH  
1008CS  
910nH  
5
D2  
D1  
1
2
1
2
6
U1  
AD9850  
D6  
E5  
E6  
C12  
3.3pF  
C14  
8.2pF  
7
J7  
BNC  
D0  
D7  
D0  
8
2Q  
1Q  
OE  
1
DGND  
DVDD  
24 GND  
DGND  
DVDD  
RESET  
IOUT  
IOUTB  
GND  
+V  
9
R4  
100k  
R6  
200⍀  
C11  
22pF  
C13  
33pF  
1D  
+V  
23  
10  
11  
12  
13  
14  
15  
16  
CLK  
W CLK  
FQ UD  
CLKIN  
22 RESET  
WCLK  
FQUD  
CLKIN  
GND  
+V  
11  
R5  
100k⍀  
C15  
22pF  
21  
20  
STROBE  
R8  
100⍀  
10 AGND  
11 AVDD  
AGND 19 GND  
AVDD  
FFQUD  
R1  
3.9k⍀  
+V  
18  
R7  
200⍀  
10mA  
R
12  
13  
14  
DACBL 17  
VINP 16  
SET  
J6  
R
SET  
QOUT  
17  
P
BNC  
QOUTB  
VINN  
15  
O
R
T
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
J8  
C1  
470pF  
BNC  
J9  
1
E1 E2 E4 E3  
J5  
+5V  
CLKIN  
R9  
2.2k⍀  
R10  
2.2k⍀  
R11  
2.2k⍀  
R3  
2.2k⍀  
R2  
50⍀  
U3  
REMOVE  
WHEN  
USING Y1  
74HCT574  
9
8
7
6
5
4
3
2
12  
13  
14  
15  
16  
17  
18  
19  
RRESET FFQUD WWCLK STROBE  
RRESET  
8D  
7D  
6D  
5D  
4D  
3D  
2D  
1D  
8Q  
7Q  
6Q  
5Q  
4Q  
3Q  
2Q  
1Q  
RESET  
+5V  
14  
WCLK  
FQUD  
WWCLK  
FFQUD  
VCC  
XTAL  
OSC  
8
CHECK  
RRESET  
OUT  
Y1  
GND  
7
WWCLK  
CHECK  
+V  
+5V  
CLK OE  
+V  
+5V  
C3  
0.1F  
C5  
0.1F  
C2  
0.1F  
C4  
0.1F  
C8  
0.1F  
C9  
0.1F  
C10  
0.1F  
11  
1
C6  
10F  
C7  
10F  
STROBE  
STROBE  
Figure 29. AD9850/CGPCB Electrical Schematic  
COMPONENT LIST  
Integrated Circuits  
U1  
Resistors  
R1  
R2  
R3, R9, R10, R11  
R4, R5  
R6, R7  
3.9 kResistor  
50 Resistor  
2.2 kResistor  
100 kResistor  
200 Resistor  
100 Resistor  
AD9850BRS (28-Lead SSOP)  
74HCT574 H-CMOS Octal Flip-Flop  
U2, U3  
Capacitors  
C1  
C2–C5, C8–C10  
C6, C7  
C11  
C12  
C13  
C14  
C15  
470 pF Ceramic Chip Capacitor  
0.1 µF Ceramic Chip Capacitor  
10 µF Tantalum Chip Capacitor  
22 pF Ceramic Chip Capacitor  
3.3 pF Ceramic Chip Capacitor  
33 pF Ceramic Chip Capacitor  
8.2 pF Ceramic Chip Capacitor  
22 pF Ceramic Chip Capacitor  
R8  
Connectors  
J2, J3, J4  
J5–J9  
Banana Jack  
BNC Connector  
Inductors  
L1  
L2  
910 nH Surface Mount  
680 nH Surface Mount  
REV. E  
17–  
AD9850  
a. AD9850/CGPCB Top Layer  
c. AD9850/CGPCB Power Plane  
b. AD9850/CGPCB Ground Plane  
d. AD9850/CGPCB Bottom Layer  
Figure 30. AD9850/CGPCB Evaluation Board Layout  
REV. E  
18–  
AD9850  
OUTLINE DIMENSIONS  
Dimensions shown in inches and (mm).  
28-Lead Shrink Small Outline Package  
(RS-28)  
0.407 (10.34)  
0.397 (10.08)  
28  
15  
14  
1
PIN 1  
0.07 (1.79)  
0.066 (1.67)  
0.078 (1.98)  
0.068 (1.73)  
8
0
0.0256  
(0.65)  
BSC  
0.015 (0.38)  
0.010 (0.25)  
0.008 (0.203)  
0.002 (0.050)  
SEATING  
PLANE  
0.009 (0.229)  
0.005 (0.127)  
0.03 (0.762)  
0.022 (0.558)  
REV. E  
19–  

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