ADF4252 [ADI]
Dual Fractional-N/Integer-N Frequency Synthesizer; 双小数N /整数N频率合成器
| 型号： | ADF4252 |
| 厂家： | 
ADI |
| 描述： | Dual Fractional-N/Integer-N Frequency Synthesizer |
| 文件： | 总28页 (文件大小：473K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Dual Fractional-N/Integer-N
Frequency Synthesizer
a
ADF4252
FEATURES
GENERAL DESCRIPTION
3.0 GHz Fractional-N/1.2 GHz Integer-N
2.7 V to 3.3 V Power Supply
Separate VP Allows Extended Tuning Voltage to 5 V
Programmable Dual Modulus Prescaler
RF: 4/5, 8/9
IF: 8/9, 16/17, 32/33, 64/65
Programmable Charge Pump Currents
3-Wire Serial Interface
Digital Lock Detect
Power-Down Mode
Programmable Modulus on Fractional-N Synthesizer
Trade-Off Noise versus Spurious Performance
The ADF4252 is a dual fractional-N/integer-N frequency
synthesizer that can be used to implement local oscillators
(LO) in the upconversion and downconversion sections of
wireless receivers and transmitters. Both the RF and IF syn-
thesizers consist of a low noise digital PFD (phase frequency
detector), a precision charge pump, and a programmable refer-
ence divider. The RF synthesizer has a ⌺-⌬-based fractional
interpolator that allows programmable fractional-N division.
The IF synthesizer has programmable integer-N counters. A
complete PLL (phase-locked loop) can be implemented if the
synthesizer is used with an external loop filter and VCO (volt-
age controlled oscillator).
Control of all the on-chip registers is via a simple 3-wire inter-
face. The devices operate with a power supply ranging from
2.7 V to 3.3 V and can be powered down when not in use.
APPLICATIONS
Base Stations for Mobile Radio (GSM, PCS, DCS,
CDMA, WCDMA)
Wireless Handsets (GSM, PCS, DCS, CDMA, WCDMA)
Wireless LANs
Communications Test Equipment
CATV Equipment
FUNCTIONAL BLOCK DIAGRAM
V
1
V
2
V
3
DV
DD
V 1
V 2
R
SET
DD
DD
DD
P
P
ADF4252
REFERENCE
4-BIT R
COUNTER
PHASE
FREQUENCY
DETECTOR
؋
2 DOUBLER
CHARGE
PUMP
REF
IN
CP
RF
REF
OUT
LOCK
DETECT
OUTPUT
MUX
MUXOUT
RF
A
IN
FRACTIONAL N
RF DIVIDER
RF
B
IN
CLK
DATA
LE
24-BIT
DATA
REGISTER
IF
B
IN
INTEGER N
IF DIVIDER
IF
A
IN
PHASE
FREQUENCY
DETECTOR
CHARGE
PUMP
CP
IF
15-BIT R
COUNTER
؋
2 DOUBLER
A
1
A
2
D
CP
1
CP 2
GND
REV. B
GND
GND
GND
GND
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks 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
Fax: 781/326-8703
www.analog.com
© 2003 Analog Devices, Inc. All rights reserved.
(VDD1 = VDD2 = V 3 = DVDD = 3 V ؎ 10%, DVDD < VP1, VP2 < 5.5 V, GND = 0 V,
ADF4252–SPECIFICATIONS1 RSET = 2.7 k⍀, dDBDm referred to 50 ⍀, TA = T to TMAX, unless otherwise noted.)
MIN
Parameter
B Version
Unit
Test Conditions/Comments
RF CHARACTERISTICS
RF Input Frequency (RFINA, RFINB)2
RF Input Sensitivity
0.25/3.0
–10/0
0.1/3.0
30
GHz min/max
dBm min/max
GHz min/max
MHz max
RF Input Frequency (RFINA, RFINB)2
RF Phase Detector Frequency
Allowable Prescaler Output Frequency
Input Level = –8/0 dBm min/max
Guaranteed by Design
375
MHz max
IF CHARACTERISTICS
IF Input Frequency (IFINA, IFINB)2
IF Input Sensitivity
50/1200
–10/0
55
MHz min/max
dBm min/max
MHz max
IF Phase Detector Frequency
Allowable Prescaler Output Frequency
Guaranteed by Design
150
MHz max
REFERENCE CHARACTERISTICS
REFIN Input Frequency
250
MHz max
For f < 10 MHz, use dc-coupled square
wave (0 to VDD).
REFIN Input Sensitivity
0.5/VDD
1
V p-p min/max AC-coupled. When dc-coupled, use
0 to VDD max (CMOS compatible).
REFIN Input Current
REFIN Input Capacitance
100
10
µA max
pF max
CHARGE PUMP
RF ICP Sink/Source
High Value
4.375
625
5
625
1
2
mA typ
µA typ
mA typ
µA typ
nA typ
% typ
See Table V
See Table IX
Low Value
High Value
Low Value
IF ICP Sink/Source
ICP Three-State Leakage Current
RF Sink and Source Current Matching
RSET Range
0.5 V < VCP < VP – 0.5
See Table V
1.5/1.6
kꢀ typ
IF Sink and Source Current Matching
2
2
2
% typ
% typ
% typ
I
CP vs. VCP
0.5 V < VCP < VP – 0.5
VCP = VP /2
ICP vs. Temperature
LOGIC INPUTS
V
INH, Input High Voltage
1.35
0.6
1
V min
VINL, Input Low Voltage
IINH/IINL, Input Current
CIN Input Capacitance
V max
µA max
pF max
10
LOGIC OUTPUTS
VOH, Output High Voltage
VOL, Output Low Voltage
VDD – 0.4
0.4
V min
V max
IOH = 0.2 mA
IOL = 0.2 mA
POWER SUPPLIES
VDD1, VDD2, VDD
DVDD
3
2.7/3.3
V min/V max
VDD
1
VP1, VP2
IDD
VDD1/5.5
V min/V max
mA typ
mA typ
3
RF + IF
RF Only
IF Only
13
10
4
16 mA max
13 mA max
5.5 mA max
mA typ
Power-Down Mode
1
µA typ
RF NOISE AND SPURIOUS CHARACTERISTICS
Noise Floor
–141
dBc/Hz typ
@ 20 MHz PFD Frequency
@ VCO Output
RFOUT = 1.8 GHz, PFD = 20 MHz
RFOUT = 1.8 GHz, PFD = 20 MHz
RFOUT = 1.8 GHz, PFD = 20 MHz
See Typical Performance Characteristics
In-Band Phase Noise Performance4
Lowest Spur Mode
–90
–95
–103
dBc/Hz typ
dBc/Hz typ
dBc/Hz typ
Low Noise and Spur Mode
Lowest Noise Mode
Spurious Signals
NOTES
1Operating Temperature Range (B Version): –40°C to +85°C.
2Use a square wave for frequencies less than fMIN
.
3RF = 1 GHz, RF PFD = 10 MHz, MOD = 4095, IF = 500 MHz, IF PFD = 200 kHz, REF = 10 MHz, VDD = 3 V, VP1 = 5 V, and VP2 = 3 V.
4The in-band phase noise is measured with the EVAL-ADF4252EB2 evaluation board and the HP5500E phase noise test system. The spectrum analyzer provides the
REFIN for the synthesizer (fREFOUT = 10 MHz @ 0 dBm). fOUT = 1.74 GHz, fREF = 20 MHz, N = 87, Mod = 100, Channel Spacing = 200 kHz, VDD = 3.3 V, and VP = 5 V.
Specifications subject to change without notice.
–2–
REV. B
ADF4252
(VDD1 = VDD2 = VDD3 = DVDD = 3 V ؎ 10%, DVDD < VP1, VP2 < 5.5 V, GND = 0 V,
TIMING CHARACTERISTICS* unless otherwise noted.)
Limit at
TMIN to TMAX
(B Version)
Parameter
Unit
Test Conditions/Comments
t1
t2
t3
t4
t5
t6
t7
10
10
10
25
25
10
20
ns min
ns min
ns min
ns min
ns min
ns min
ns min
LE Setup Time
DATA to CLOCK Setup Time
DATA to CLOCK Hold Time
CLOCK High Duration
CLOCK Low Duration
CLOCK to LE Setup Time
LE Pulse Width
*Guaranteed by design, but not production tested.
t4
t5
CLOCK
t3
t2
DB1
(CONTROL BIT C2)
DB0 (LSB)
(CONTROL BIT C1)
DATA
LE
DB22
DB2
DB23 (MSB)
t1
t6
t7
LE
Figure 1. Timing Diagram
REV. B
–3–
ADF4252
ABSOLUTE MAXIMUM RATINGS1, 2
ORDERING GUIDE
(TA = 25°C, unless otherwise noted.)
VDD1, VDD2, VDD3, DVDD to GND3 . . . . . . . . –0.3 V to +4 V
REFIN, RFINA, RFINB to GND . . . . . . –0.3 V to VDD + 0.3 V
Temperature
Range
Package
Option*
Mode
VP1, VP2 to GND . . . . . . . . . . . . . . . . . . . . . –0.3 V to +5.8 V
ADF4252BCP
ADF4252BCP-REEL
ADF4252BCP-REEL7
EVAL–ADF4252EB1
EVAL–ADF4252EB2
–40ºC to +85ºC
–40ºC to +85ºC
–40ºC to +85ºC
CP-24
CP-24
CP-24
VP1, VP2 to VDD
1 . . . . . . . . . . . . . . . . . . . . . –3.3 V to +3.5 V
Digital I/O Voltage to GND . . . . . . . . –0.3 V to VDD + 0.3 V
Analog I/O Voltage to GND . . . . . . . . –0.3 V to VDD + 0.3 V
Operating Temperature Range
Industrial (B Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Maximum Junction Temperature . . . . . . . . . . . . . . . . . 150°C
CSP ꢀJA Thermal Impedance . . . . . . . . . . . . . . . . . . . 122°C/W
Soldering Reflow Temperature
*CP = Chip Scale Package
PIN CONFIGURATION
Vapor Phase (60 sec max) . . . . . . . . . . . . . . . . . . . . . 240°C
IR Reflow (20 sec max) . . . . . . . . . . . . . . . . . . . . . . . 240°C
NOTES
1Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only and functional operation of
the device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
2This device is a high performance RF integrated circuit with an ESD rating
of <2 kΩ, and it is ESD sensitive. Proper precautions should be taken for handling
and assembly.
CP
1
1 2
18 CP
17 DV
16 IF
2
GND
PIN 1
RF
INDICATOR
CP
RF A 3
RF B 4
IN
GND
DD
A
IN
IN
B
ADF4252
15 IF
IN
TOP VIEW
A
1 5
14 A
13 R
2
GND
GND
SET
(Not to Scale)
MUXOUT 6
3GND = CPGND1, AGND1, DGND, AGND2, and CPGND2.
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
ADF4252 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.
–4–
REV. B
ADF4252
PIN FUNCTION DESCRIPTIONS
Mnemonic
CPRF
Function
RF Charge Pump Output. This is normally connected to a loop filter that drives the input to an external VCO.
RF Charge Pump Ground.
CPGND1
RFINA
Input to the RF Prescaler. This small signal input is normally taken from the VCO.
Complementary Input to the RF Prescaler.
RFINB
AGND1
Analog Ground for the RF Synthesizer.
MUXOUT
This multiplexer output allows either the RF or IF lock detect, the scaled RF or IF, or the scaled reference fre-
quency to be accessed externally.
REFIN
Reference Input. This is a CMOS input with a nominal threshold of VDD/2 and an equivalent input resistance of
100 kΩ. This input can be driven from a TTL or CMOS crystal oscillator.
REFOUT
DGND
Reference Output.
Digital Ground for the Fractional Interpolator.
CLK
Serial Clock Input. This serial clock is used to clock in the serial data to the registers. The data is latched into the
shift register on the CLK rising edge. This input is a high impedance CMOS input.
DATA
LE
Serial Data Input. The serial data is loaded MSB first with the three LSBs being the control bits. This input is a
high impedance CMOS input.
Load Enable, CMOS Input. When LE goes high, the data stored in the shift registers is loaded into one of the
seven latches, the latch being selected using the control bits.
RSET
Connecting a resistor between this pin and ground sets the minimum charge pump output current. The relationship
between ICP and RSET is
1.6875
RSET
ICPmin
=
Therefore, with RSET = 2.7 kΩ, ICPmin = 0.625 mA.
Ground for the IF Synthesizer.
AGND
2
IFINB
IFINA
DVDD
Complementary Input to the IF Prescaler.
Input to the IF Prescaler. This small signal input is normally taken from the IF VCO.
Positive Power Supply for the Fractional Interpolator Section. Decoupling capacitors to the ground plane should
be placed as close as possible to this pin. DVDD must have the same voltage as VDD1, VDD2, and VDD3.
CPGND2
CPIF
IF Charge Pump Ground.
IF Charge Pump Output. This is normally connected to a loop filter that drives the input to an external VCO.
VP2
IF Charge Pump Power Supply. Decoupling capacitors to the ground plane should be placed as close as possible
to this pin. This voltage should be greater than or equal to VDD2.
V
V
V
DD2
DD3
DD1
Positive Power Supply for the IF Section. Decoupling capacitors to the ground plane should be placed as close as
possible to this pin. VDD2 has a value 3 V 10%. VDD2 must have the same voltage as VDD1, VDD3, and DVDD
Positive Power Supply for the RF Digital Section. Decoupling capacitors to the ground plane should be placed as close
as possible to this pin. VDD3 has a value 3 V 10%. VDD3 must have the same voltage as VDD1, VDD2, and DVDD
Positive Power Supply for the RF Analog Section. Decoupling capacitors to the ground plane should be placed as close
as possible to this pin. VDD1 has a value 3 V 10%. VDD1 must have the same voltage as VDD2, VDD3, and DVDD
.
.
.
VP1
RF Charge Pump Power Supply. Decoupling capacitors to the ground plane should be placed as close as possible
to this pin. This voltage should be greater than or equal to VDD1.
REV. B
–5–
ADF4252
V
1
V
2
V
3
DV
DD
V 1
V 2
R
SET
DD
DD
DD
P
P
ADF4252
REFERENCE
4-BIT R
COUNTER
PHASE
FREQUENCY
DETECTOR
ꢀ2
DOUBLER
CHARGE
PUMP
REF
IN
CP
RF
REF
OUT
V
DD
HIGH Z
LOCK
DETECT
D
GND
OUTPUT
MUX
MUXOUT
V
DD
RF
A
IN
N
R
DIV
COUNTER
RF
B
IN
N
DIV
THIRD ORDER
FRACTIONAL
INTERPOLATOR
CLK
DATA
LE
24-BIT
DATA
REGISTER
FRACTION
REG
MODULUS
REG
INTEGER
REG
6-BIT IF A
COUNTER
IF
B
IN
IF PRE-
SCALER
IF
A
IN
12-BIT IF B
COUNTER
PHASE
FREQUENCY
DETECTOR
CHARGE
PUMP
CP
IF
15-BIT R
COUNTER
ꢀ2
DOUBLER
A
1
A
2
D
CP
1
CP 2
GND
GND
GND
GND
GND
Figure 2. Detailed Functional Block Diagram
–6–
REV. B
Typical Performance Characteristics–ADF4252
TPC plots 1 to 12 attained using EVAL-ADF4252EB1;
measurements from HP8562E spectrum analyzer.
0
0
V
= 3V, V = 5V
P
= 1.875mA
DD
V
= 3V, V = 5V
P
= 1.875mA
DD
I
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
REFERENCE
LEVEL = –4.2dBm
CP
I
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
REFERENCE
LEVEL = –4.2dBm
CP
PFD FREQUENCY = 10MHz
PFD FREQUENCY = 10MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 1kHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 10Hz
–50dBc@
100kHz
–99.19dBc/Hz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
–2kHz
–1kHz
1.7518GHz
1kHz
2kHz
FREQUENCY
TPC 4. Spurious Plot, Lowest Noise Mode,
1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 1. Phase Noise Plot, Lowest Noise Mode,
1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
0
0
V = 3V, V = 5V
DD P
V
= 3V, V = 5V
P
= 1.875mA
DD
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
I = 1.875mA
REFERENCE
LEVEL = –4.2dBm
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
I
CP
REFERENCE
LEVEL = –4.2dBm
CP
PFD FREQUENCY = 10MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
PFD FREQUENCY = 10MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 1kHz
RBW = 10Hz
–51dBc@
100kHz
–90.36dBc/Hz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
–2kHz
–1kHz
1.7518GHz
FREQUENCY
1kHz
2kHz
TPC 5. Spurious Plot, Low Noise and Spur Mode,
1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 2. Phase Noise Plot, Low Noise and Spur
Mode, 1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
0
0
V = 3V, V = 5V
DD P
V
= 3V, V = 5V
P
= 1.875mA
DD
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
I = 1.875mA
REFERENCE
LEVEL = –4.2dBm
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
I
CP
REFERENCE
LEVEL = –4.2dBm
CP
PFD FREQUENCY = 10MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
PFD FREQUENCY = 10MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 1kHz
RBW = 10Hz
–72dBc@
100kHz
–85.86dBc/Hz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
–2kHz
–1kHz
1.7518GHz
FREQUENCY
1kHz
2kHz
TPC 6. Spurious Plot, Lowest Spur Mode,
1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 3. Phase Noise Plot, Lowest Spur Mode,
1.7518 GHz RFOUT, 10 MHz PFD Frequency,
200 kHz Channel Step Resolution
REV. B
–7–
ADF4252
0
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
V
= 3V, V = 5V
= 1.875mA
V = 3V, V = 5V
DD P
DD
P
I
I
= 1.875mA
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
CP
REFERENCE
LEVEL = –4.2dBm
CP
REFERENCE
LEVEL = –4.2dBm
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 10Hz
RBW = 1kHz
–53dBc@
100kHz
–102dBc/Hz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
–2kHz
–1kHz
1.7518GHz
1kHz
2kHz
FREQUENCY
TPC 7. Phase Noise Plot, Lowest Noise Mode,
1.7518 GHz RFOUT, 20 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 10. Spurious Plot, Lowest Noise Mode,
1.7518 GHz RFOUT, 20 MHz PFD Frequency,
200 kHz Channel Step Resolution
0
0
V
= 3V, V = 5V
P
V
= 3V, V = 5V
DD
DD P
I
= 1.875mA
I
= 1.875mA
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
REFERENCE
LEVEL = –4.2dBm
REFERENCE
LEVEL = –4.2dBm
CP
CP
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 10Hz
RBW = 1kHz
–63.2dBc@
100kHz
–93.86dBc/Hz
–2kHz
–1kHz
1.7518GHz
1kHz
2kHz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
FREQUENCY
TPC 8. Phase Noise Plot, Low Noise and Spur
Mode, 1.7518 GHz RFOUT, 20 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 11. Spurious Plot, Low Noise and Spur Mode,
1.7518 GHz RFOUT, 20 MHz PFD Frequency, 200 kHz
Channel Step Resolution
0
0
V
= 3V, V = 5V
P
V
= 3V, V = 5V
DD
DD P
I
= 1.875mA
I
= 1.875mA
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
REFERENCE
LEVEL = –4.2dBm
REFERENCE
LEVEL = –4.2dBm
CP
CP
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
PFD FREQUENCY = 20MHz
CHANNEL STEP = 200kHz
LOOP BANDWIDTH = 20kHz
FRACTION = 59/100
RBW = 10Hz
RBW = 1kHz
–72.33dBc@
100kHz
–89.52dBc/Hz
–2kHz
–1kHz
1.7518GHz
1kHz
2kHz
–400kHz
–200kHz 1.7518GHz
FREQUENCY
200kHz
400kHz
FREQUENCY
TPC 9. Phase Noise Plot, Lowest Spur Mode,
1.7518 GHz RFOUT, 20 MHz PFD Frequency,
200 kHz Channel Step Resolution
TPC 12. Spurious Plot, Lowest Spur Mode,
1.7518 GHz RFOUT, 20 MHz PFD Frequency,
200 kHz Channel Step Resolution
–8–
REV. B
ADF4252
–70
–75
–20
–30
–40
–50
–60
–70
–80
–90
–100
–80
–85
LOWEST SPUR MODE
–90
LOWEST NOISE MODE
–95
–100
–105
–110
–115
–120
LOW NOISE AND SPUR MODE
LOWEST NOISE MODE
–110
–120
LOWEST SPUR MODE
1.430
1.435
1.440
1.445
1.450
1.455
1.460
1.430
1.435
1.440
FREQUENCY (GHz)
1.445
1.450
1.455
1.460
1.460
1.460
FREQUENCY (GHz)
TPC 13. In-Band Phase Noise vs. Frequency*
TPC 16. 400 kHz Spur vs. Frequency*
–10
–20
–30
–40
–20
–30
–40
–50
LOWEST NOISE MODE
–50
–60
LOWEST NOISE MODE
–60
–70
–80
–90
–70
–80
–90
–100
–110
–120
–100
LOWEST SPUR MODE
LOWEST SPUR MODE
–110
1.430
1.435
1.440
1.445
1.450
1.455
1.460
1.430
1.435
1.440
FREQUENCY (GHz)
1.445
1.450
1.455
FREQUENCY (GHz)
TPC 14. 100 kHz Spur vs. Frequency*
TPC 17. 600 kHz Spur vs. Frequency*
–20
–30
–20
–30
–40
–40
–50
–50
–60
–60
LOWEST NOISE MODE
–70
–70
–80
–80
–90
–90
–100
–110
–120
–100
–110
–120
LOWEST NOISE MODE
LOWEST SPUR MODE
LOWEST SPUR MODE
1.430
1.435
1.440
1.445
1.450
1.455
1.460
1.430
1.435
1.440
1.445
1.450
1.455
FREQUENCY (GHz)
FREQUENCY (GHz)
TPC 15. 200 kHz Spur vs. Frequency*
TPC 18. 3 MHz Spur vs. Frequency*
*Across all fractional channel steps from f = 0/130 to f = 129/130.
RFOUT = 1.45 GHz, Int Reg = 55, Ref = 26 MHz, and LBW = 40 kHz. Plots attained using EVAL-ADF4252EB2 evaluation board.
REV. B
–9–
ADF4252
–120
–130
–140
–150
–160
–170
–180
0
V
V
= 3V
DD
= 3V
P
–5
–10
–15
–20
–25
–30
PRESCALER = 4/5
PRESCALER = 8/9
–35
0
1
2
3
4
5
6
10k
100k
1M
10M
FREQUENCY (GHz)
PHASE DETECTOR FREQUENCY (Hz)
TPC 19. RF Input Sensitivity
TPC 22. Phase Noise (Referred to CP Output) vs.
PFD Frequency, IF Side
6
4
2
0
V
= 3V
DD
V 2 = 3V
P
5
10
15
20
25
30
35
40
V
= 3V
DD
V 1 = 5.5V
P
0
–2
–4
–6
–0.4
0.1
0.6
1.1
1.6
0
0.5 1.0 1.5 2.0
3.0 3.5 4.0 4.5
(V)
5.5
2.5
V
CP
5.0
IF INPUT FREQUENCY (GHz)
TPC 20. IF Input Sensitivity
TPC 23. RF Charge Pump Output Characteristics
–120
–130
–140
–150
–160
6
4
2
V
V
= 3V
DD
= 5V
P
V
= 3V
DD
P
V 2 = 3V
0
–2
–4
–6
–170
–180
10k
100k
1M
0
10M
0.5
1.0
1.5
(V)
2.0
2.5
3.0
PHASE DETECTOR FREQUENCY (Hz)
V
CP
TPC 21. Phase Noise (Referred to CP Output) vs.
PFD Frequency, RF Side
TPC 24. IF Charge Pump Output Characteristics
–10–
REV. B
ADF4252
CIRCUIT DESCRIPTION
Reference Input Section
REFIN = the reference input frequency, D = RF REFIN doubler
bit, R = the preset divide ratio of the binary 4-bit program-
mable reference counter (1 to 15), INT = the preset divide ratio of
the binary 8-bit counter (31 to 255), MOD = the preset modulus
ratio of binary 12-bit programmable FRAC counter (2 to 4095),
and FRAC = the preset fractional ratio of the binary 12-bit
programmable FRAC counter (0 to MOD).
The reference input stage is shown in Figure 3. SW1 and SW2
are normally closed switches. SW3 is normally open. When
power-down is initiated, SW3 is closed and SW1 and SW2 are
opened. This ensures that there is no loading of the REFIN pin
on power-down.
POWER-DOWN
CONTROL
RF N DIVIDER
N = INT + FRAC/MOD
100kꢁ
FROM RF
INPUT STAGE
NC
TO PFD
N-COUNTER
SW2
REF
IN
NC
TO R
BUFFER
XOEB
COUNTER
THIRD ORDER
FRACTIONAL
INTERPOLATOR
SW1
SW3
REF
OUT
NO
FRAC
VALUE
INT
REG
MOD
REG
NC = NORMALLY CLOSED
NO = NORMALLY OPEN
Figure 3. Reference Input Stage
RF and IF Input Stage
The RF input stage is shown in Figure 4. The IF input stage is
the same. It is followed by a two-stage limiting amplifier to
generate the CML clock levels needed for the N counter.
Figure 5. N Counter
RF R Counter
The 4-bit RF R counter allows the input reference frequency
(REFIN) to be divided down to produce the reference clock to
the RF PFD. Division ratios from 1 to 15 are allowed.
1.6V
BIAS
GENERATOR
V
1
DD
2kꢁ
2kꢁ
IF R Counter
The 15-bit IF R counter allows the input reference frequency
(REFIN) to be divided down to produce the reference clock to
the IF PFD. Division ratios from 1 to 32767 are allowed.
RF
RF
A
B
IN
IF Prescaler (P/P + 1)
IN
The dual modulus IF prescaler (P/P + 1), along with the IF A
and B counters, enables the large division ratio, N, to be realized
(N = PB + A). Operating at CML levels, it takes the clock from
the IF input stage and divides it down to a manageable frequency
for the CMOS IF A and B counters.
A
GND
Figure 4. RF Input Stage
IF A and B Counters
RF INT Divider
The RF INT CMOS counter allows a division ratio in the PLL
feedback counter. Division ratios from 31 to 255 are allowed.
The IF A and B CMOS counters combine with the dual modulus
IF prescaler to allow a wide ranging division ratio in the PLL
feedback counter. The counters are guaranteed to work when the
prescaler output is 150 MHz or less.
INT, FRAC, MOD, and R Relationship
The INT, FRAC, and MOD values, in conjunction with the
RF R counter, make it possible to generate output frequencies
that are spaced by fractions of the RF phase frequency detector
(PFD). The equation for the RF VCO frequency (RFOUT) is
Pulse Swallow Function
The IF A and B counters, in conjunction with the dual modulus
IF prescaler, make it possible to generate output frequencies
that are spaced only by the reference frequency divided by R.
See Device Programming after Initial Power-Up section for
examples. The equation for the IF VCO (IFOUT) frequency is
FRAC
RFOUT = FPFD × INT +
(1)
MOD
IFOUT = P × B + A × F
(3)
(
[
)
]
PFD
where RFOUT is the output frequency of external voltage controlled
oscillator (VCO).
where IFOUT = the output frequency of the external voltage controlled
oscillator (VCO), P = the preset modulus of IF dual modulus
prescaler, B = the preset divide ratio of the binary 12-bit counter
(3 to 4095), and A = the preset divide ratio of the binary 6-bit
swallow counter (0 to 63). FPFD is obtained using Equation 2.
1+ D
R
(
)
(2)
FPFD = REFIN
×
REV. B
–11–
ADF4252
Phase Frequency Detector (PFD) and Charge Pump
The PFD takes inputs from the R counter and N counter and
produces an output proportional to the phase and frequency
difference between them. Figure 6 is a simplified schematic. The
Lock Detect
MUXOUT can be programmed for two types of lock detect: digital
and analog. Digital is active high. The N-channel open-drain
analog lock detect should be operated with an external pull-up
resistor of 10 kΩ nominal. When lock has been detected, this
output will be high with narrow low going pulses.
antibacklash pulse. This pulse ensures that there is no dead zone
in the PFD transfer function and minimizes phase noise and
reference spurs.
Input Shift Register
Data is clocked in on each rising edge of CLK. The data is
clocked in MSB first. Data is transferred from the input register
to one of seven latches on the rising edge of LE. The destination
latch is determined by the state of the three control bits (C2, C1,
and C0) in the shift register. These are the three LSBs: DB2,
DB1, and DB0, as shown in Figure 1. The truth table for these
bits is shown in Table I. Table II summarizes how the registers
are programmed.
U1
HI
D1
UP
Q1
+IN
CLR1
CHARGE
PUMP
DELAY
ELEMENT
CP
U3
Table I. Control Bit Truth Table
C2
C1
C0
Data Latch
0
0
0
0
1
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
RF N Divider Reg
RF R Divider Reg
RF Control Reg
Master Reg
IF N Divider Reg
IF R Divider Reg
IF Control Reg
CLR2
D2
HI
DOWN
Q2
–IN
U2
Figure 6. PFD Simplified Schematic
MUXOUT and Lock Detect
The output multiplexer on the ADF4252 allows the user to
access various internal points on the chip. The state of MUXOUT
is controlled by M4, M3, M2, and M1 in the master register.
Table I shows the full truth table. Figure 7 shows the MUXOUT
section in block diagram format.
DV
DD
LOGIC LOW
IF ANALOG LOCK DETECT
IF R DIVIDER OUTPUT
IF N DIVIDER OUTPUT
RF ANALOG LOCK DETECT
IF/RF ANALOG LOCK DETECT
IF DIGITAL LOCK DETECT
LOGIC HIGH
MUXOUT
MUX
CONTROL
RF R DIVIDER OUTPUT
RF N DIVIDER OUTPUT
THREE STATE OUTPUT
RF DIGITAL LOCK DETECT
RF/IF DIGITAL LOCK DETECT
LOGIC HIGH
LOGIC LOW
D
GND
Figure 7. MUXOUT Circuit
–12–
REV. B
ADF4252
Table II. Register Summary
RF N DIVIDER REG
CONTROL
BITS
8-BIT RF INTEGER VALUE (INT)
12-BIT RF FRACTIONAL VALUE (FRAC)
DB23 DB22 DB21
DB20 DB19 DB18
N6 N5 N4
DB17 DB16 DB15
N3 N2 N1
DB14 DB13 DB12
F12 F11 F10
DB11 DB10
F9
F8
DB9
F7
DB8
F6
DB7
F5
DB6
F4
DB5
F3
DB4
F2
DB3
F1
DB2
DB1
DB0
P1
N8
N7
C3 (0) C2 (0) C1 (0)
RF R DIVIDER REG
CONTROL
BITS
4-BIT RF R COUNTER
12-BIT INTERPOLATOR MODULUS VALUE (MOD)
DB20 DB19
P3 P2
DB18 DB17 DB16 DB15 DB14 DB13
R2
DB12 DB11 DB10
M8
DB9
M7
DB8
M6
DB7
M5
DB6
M4
DB5
M3
DB4
M2
DB3
M1
DB2
DB1
DB0
C3 (0)
C2 (0) C1 (1)
R4
M12
M11
R3
R1
M10
M9
RF CONTROL REG
RF CP
CURRENT
SETTING
CONTROL
BITS
RESERVED
DB15 DB14 DB13 DB12 DB11 DB10
N3 T3 T2 T1 N2 CP2
DB9
CP1
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
0
P8
N1
P6
P5
P4
C3 (0) C2 (1) C1 (0)
MASTER REG
CONTROL
BITS
MUXOUT
DB10
M4
DB9
DB8
M2
DB7
M1
DB6
P12
DB5
P11
DB4
P10
DB3
P9
DB2
DB1
DB0
M3
C3 (0) C2 (1) C1 (1)
IF N DIVIDER REG
CONTROL
BITS
12-BIT IF B COUNTER
6-BIT IF A COUNTER
IF PRESCALER
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10
DB9
B1
DB8
A6
DB7
A5
DB6
A4
DB5
A3
DB4
A2
DB3
A1
DB2
DB1
DB0
P15
P14
P13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
C3 (1) C2 (0) C1 (0)
IF R DIVIDER REG
CONTROL
BITS
15-BIT IF R COUNTER
DB18 DB17 DB16 DB15 DB14 DB13
P16 R15 R14 R13 R12 R11
DB12 DB11 DB10
R10 R9 R8
DB9
R7
DB8
R6
DB7
R5
DB6
R4
DB5
R3
DB4
R2
DB3
R1
DB2
DB1
DB0
C3 (1) C2 (0) C1 (1)
IF CONTROL REG
RF PHASE
RESYNC
IF CP CURRENT
SETTING
CONTROL
BITS
RESERVED
DB15 DB14 DB13
DB12 DB11 DB10
T7 PR1 CP3
DB9
CP2
DB8
CP1
DB7
P21
DB6
P20
DB5
P19
DB4
P18
DB3
P17
DB2
DB1
DB0
PR3
PR2
T8
C3 (1) C2 (1) C1 (0)
REV. B
–13–
ADF4252
Table III. RF N Divider Register Map
CONTROL
BITS
8-BIT RF INTEGER VALUE (INT)
12-BIT RF FRACTIONAL VALUE (FRAC)
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
P1
N8
N7
N6
N5
N4
N3
N2
N1
F12
F11
F10
F9
F8
F7
F6
F5
F4
F3
F2
F1
C1 (0)
C3 (0) C2 (0)
F12
F11
F10
F3
F2
0
0
1
1
.
.
.
0
F1
0
1
0
1
.
.
.
0
FRACTIONAL VALUE (FRAC)
0
1
2
3
.
.
.
0
0
0
0
.
.
.
1
0
0
0
0
.
.
.
1
0
0
0
0
.
.
.
1
..........
..........
..........
..........
..........
..........
..........
..........
0
0
0
0
.
.
.
1
RESERVED
RESERVED
P1
0
4092
1
1
1
1
1
1
1
1
1
..........
..........
..........
1
1
1
0
1
1
1
0
1
4093
4094
4095
RF INTEGER
VALUE (INT)*
N8
0
0
0
0
.
N7
0
0
0
0
.
N6
0
1
1
1
.
N5
N4
N3
1
0
0
0
.
N2
1
0
0
1
.
N1
1
0
1
0
.
1
0
0
0
.
1
0
0
0
.
31
32
33
34
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
1
1
1
0
1
253
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
254
255
*WHEN P = 8/9, N
= 91
MIN
–14–
REV. B
ADF4252
Table IV. RF R Divider Register Map
CONTROL
BITS
12-BIT INTERPOLATOR MODULUS VALUE (MOD)
4-BIT RF R COUNTER
DB20 DB19 DB18 DB17 DB16 DB15
DB14 DB13 DB12 DB11 DB10
DB9
M7
DB8
M6
DB7
M5
DB6
M4
DB5
M3
DB4
M2
DB3
M1
DB2
DB1
DB0
C3 (0)
P3
P2
R4
R3
R2
R1
M12
M11
M10
M9
C2 (0) C1 (1)
M8
INTERPOLATOR MODULUS
M12
M11
M10
M3
M2
M1
VALUE (MOD) DIVIDE RATIO
0
0
0
.
.
.
0
0
0
.
.
.
0
0
0
.
.
.
..........
..........
..........
..........
..........
..........
..........
0
0
1
.
.
.
1
1
0
.
.
.
0
1
0
.
.
.
2
3
4
.
.
.
P2
RF REF
IN
DOUBLER
0
1
DISABLED
ENABLED
1
1
1
1
0
0
4092
1
1
1
1
1
1
1
1
1
..........
..........
..........
1
1
1
0
1
1
1
0
1
4093
4094
4095
P3
RF PRESCALER
0
1
4/5
8/9
RF R COUNTER
R4
0
0
0
.
R3
0
0
0
.
R2
0
1
1
.
R1
DIVIDE RATIO
1
0
1
.
1
2
3
.
.
.
.
.
.
.
.
.
.
.
1
1
0
1
13
1
1
1
1
1
1
0
1
14
15
REV. B
–15–
ADF4252
Table V. RF Control Register Map
RF CP
CURRENT
SETTING
CONTROL
BITS
RESERVED
DB15 DB14 DB13 DB12
DB11 DB10
DB9
CP1
DB8
0
DB7
P8
DB6
N1
DB5
P6
DB4
P5
DB3
P4
DB2
DB1
DB0
CP2
N3
T3
T2
T1
N2
C2 (1) C1 (0)
C3 (0)
THESE BITS SHOULD
EACH BE SET TO 0 FOR
NORMAL OPERATION
P4
RF COUNTER
RESET
0
1
DISABLED
ENABLED
N3
N2
N1
NOISE AND SPUR
SETTING
P5
0
1
RF CP THREE-STATE
DISABLED
THREE-STATE
0
0
1
0
0
1
0
1
1
LOWEST SPUR
LOW NOISE AND SPUR
LOWEST NOISE
P6
0
1
RF POWER-DOWN
DISABLED
ENABLED
I
(mA)
CP
CP2
CP1
1.5k
2.7k
5.6k
0
0
1
1
0
1
0
1
1.125
3.375
5.625
7.7875
0.625
1.875
3.125
4.375
0.301
0.904
1.506
2.109
P8
0
RF PD POLARITY
NEGATIVE
1
POSITIVE
–16–
REV. B
ADF4252
Table VI. Master Register Map
CONTROL
BITS
MUXOUT
DB10
M4
DB9
M3
DB8
M2
DB7
M1
DB6
P12
DB5
P11
DB4
P10
DB3
P9
DB2
DB1
DB0
C3 (0)
C2 (1) C1 (1)
MUXOUT
P9
COUNTER RESET
M4
M1
M3
M2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
LOGIC LOW
DISABLED
ENABLED
0
1
IF ANALOG LOCK DETECT
IF R DIVIDER OUTPUT
IF N DIVIDER OUTPUT
RF ANALOG LOCK DETECT
RF/IF ANALOG LOCK DETECT
IF DIGITAL LOCK DETECT
LOGIC HIGH
RF R DIVIDER OUTPUT
RF N DIVIDER OUTPUT
THREE-STATE OUTPUT
LOGIC LOW
P10
CP THREE-STATE
0
1
DISABLED
THREE-STATE
P11
POWER-DOWN
0
1
DISABLED
ENABLED
RF DIGITAL LOCK DETECT
RF/IF DIGITAL LOCK DETECT
LOGIC HIGH
LOGIC LOW
XO DISABLE
XO ENABLED (REF
P12
0
1
= REF )
IN
= LOGIC LOW)
OUT
XO DISABLED (REF
OUT
(REF
= LOGIC HIGH WHEN IN POWER-DOWN)
OUT
REV. B
–17–
ADF4252
Table VII. IF N Divider Register Map
IF
12-BIT IF B COUNTER*
6-BIT IF A COUNTER*
CONTROL
BITS
PRESCALER*
DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12
DB11 DB10
B3 B2
DB9
B1
DB8
A6
DB7
A5
DB6
A4
DB5
A3
DB4
A2
DB3
A1
DB2
DB1
DB0
DB20
B12
DB23 DB22
P15
P14
DB21
P13
C2 (0) C1 (0)
B11
B10
B9
B8
B7
B6
B5
B4
C3 (1)
P14
P13
PRESCALER VALUE
0
0
1
1
0
1
0
1
8/9
16/17
32/33
64/65
A COUNTER
DIVIDE RATIO
A6
A5
..........
A2
A1
0
0
0
0
.
.
.
1
0
0
0
0
.
.
.
1
..........
..........
..........
..........
..........
..........
..........
..........
0
0
1
1
.
.
.
0
0
1
0
1
.
.
.
0
0
1
2
3
.
.
.
60
P15
IF CP GAIN
0
1
DISABLED
ENABLED
1
1
1
1
1
1
..........
..........
..........
0
1
1
1
0
1
61
62
63
B12
B11
B10
B3
B2
B1
B COUNTER DIVIDE RATIO
0
0
.
.
.
0
0
.
.
.
0
0
.
.
.
..........
..........
..........
..........
..........
..........
0
1
.
.
.
1
0
.
.
.
1
0
.
.
.
3
4
.
.
.
1
1
1
1
0
0
4092
1
1
1
1
1
1
1
1
1
..........
..........
..........
1
1
1
0
1
1
1
0
1
4093
4094
4095
*N = BP + A, P IS PRESCALER VALUE. B MUST BE GREATER THAN OR EQUAL TO A FOR CONTIGUOUS VALUES OF N, NMIN IS (P2 – P) .
–18–
REV. B
ADF4252
Table VIII. IF R Divider Register Map
CONTROL
BITS
15-BIT IF R COUNTER
DB18
P16
DB17 DB16 DB15
DB14
R12
DB13 DB12
R11 R10
DB11 DB10
DB9
R7
DB8
R6
DB7
R5
DB6
R4
DB5
R3
DB4
R2
DB3
R1
DB2
DB1
DB0
C3 (1)
R8
R9
R14
R15
R13
C2 (0) C1 (1)
R15
0
0
0
0
.
.
.
R14
R13
R12
..........
..........
..........
..........
..........
..........
..........
..........
..........
R3
0
0
0
1
.
.
.
1
R2
0
1
1
0
.
.
.
0
R1
1
0
1
0
.
.
.
0
DIVIDE RATIO
1
2
3
4
.
.
.
0
0
0
0
.
.
.
1
0
0
0
0
.
.
.
1
0
0
0
0
.
.
.
1
16380
32764
1
1
1
1
1
1
1
1
1
..........
..........
..........
1
1
1
0
1
1
1
0
1
16381
16382
16383
32765
32766
32767
P16
IF REF
IN
DOUBLER
DISABLED
ENABLED
0
1
REV. B
–19–
ADF4252
Table IX. IF Control Register Map
RF PHASE
RESYNC
IF CP CURRENT
SETTING
CONTROL
BITS
RESERVED
DB15 DB14 DB13 DB12
DB11 DB10
CP3
DB9
CP2
DB8
CP1
DB7
P21
DB6
P20
DB5
P19
DB4
P18
DB3
P17
DB2
DB1
DB0
PR3
PR2
T8
T7
PR1
C2 (1) C1 (0)
C3 (1)
THESE BITS
SHOULD BE SET
TO 0 FOR NORMAL
OPERATION
P17
0
IF COUNTER RESET
DISABLED
1
ENABLED
PR3
0
1
PR2
0
1
PR1
0
1
RF PHASE RESYNC
DISABLED
ENABLED
P18
0
1
IF CP THREE-STATE
DISABLED
THREE-STATE
P19
0
1
IF POWER-DOWN
DISABLED
ENABLED
I
(mA)
CP
IF CP3
IF CP2
IF CP1
1.5k
1.125
2.25
3.375
4.5
5.625
6.75
7.7875
9
2.7k
5.6k
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0.625
1.25
1.875
2.5
3.125
3.75
4.375
5.0
0.301
0.602
0.904
1.205
1.506
1.808
2.109
2.411
P20
0
1
IF LDP
3
5
P21
0
1
IF PD POLARITY
NEGATIVE
POSITIVE
–20–
REV. B
ADF4252
RF N DIVIDER REGISTER
(Address R0)
RF CONTROL REGISTER
(Address R2)
With R0[2, 1, 0] set to [0, 0, 0], the on-chip RF N divider register
will be programmed. Table III shows the input data format for
programming this register.
With R2[2, 1, 0] set to [0, 1, 0], the on-chip RF control register
will be programmed. Table V shows the input data format for
programming this register. Upon initialization, DB15–DB11
should all be set to 0.
8-Bit RF INT Value
These eight bits control what is loaded as the INT value. This is
used to determine the overall feedback division factor. It is used in
Equation 1.
Noise and Spur Setting
The noise and spur setting (R2[15, 11, 06]) is a feature that
allows the user to optimize his or her design either for improved
spurious performance or for improved phase noise performance.
When set to [0, 0, 0], the lowest spurs setting is chosen. Here,
dither is enabled. This randomizes the fractional quantization
noise so that it looks more like white noise than spurious noise.
This means that the part is optimized for improved spurious
performance. This operation would normally be used when the
PLL closed-loop bandwidth is wide1, for fastlocking applications.
A wide-loop filter does not attenuate the spurs to a level that a
narrow-loop2 bandwidth would. When this bit is set to [0, 0, 1],
the low noise and spur setting is enabled. Here, dither is disabled.
This optimizes the synthesizer to operate with improved noise
performance. However, the spurious performance is degraded in
this mode compared to lowest spurs setting. To improve noise
performance even further, another option is available that reduces
the phase noise. This is the lowest noise setting [1, 1, 1]. As well
as disabling the dither, it also ensures the charge pump is oper-
ating in an optimum region for noise performance. This setting is
extremely useful where a narrow-loop filter bandwidth is available.
The synthesizer ensures extremely low noise and the filter attenu-
ates the spurs. The Typical Performance Characteristics (TPCs)
give the user an idea of the trade-off in a typical WCDMA setup
for the different noise and spur settings.
12-Bit RF FRAC Value
These 12 bits control what is loaded as the FRAC value into the
fractional interpolator. This is part of what determines the overall
feedback division factor. It is used in Equation 1. The FRAC
value must be less than or equal to the value loaded into the
MOD register.
RF R DIVIDER REGISTER
(Address R1)
With R1[2, 1, 0] set to [0, 0, 1], the on-chip RF R divider register
will be programmed. Table IV shows the input data format for
programming this register.
RF Prescaler (P/P + 1)
The RF dual-modulus prescaler (P/P +1), along with the INT,
FRAC, and MOD counters, determine the overall division ratio
from the RFIN to the PFD input. Operating at CML levels, it
takes the clock from the RF input stage and divides it down to
a manageable frequency for the CMOS counters. It is based on
a synchronous 4/5 core (see Table IV).
RF REFIN Doubler
Setting this bit to 0 feeds the REFIN signal directly to the 4-bit
RF R counter, disabling the doubler. Setting this bit to 1 multiplies
the REFIN frequency by a factor of 2 before feeding into the
4-bit RF R counter. When the doubler is disabled, the REFIN
falling edge is the active edge at the PFD input to the fractional-N
synthesizer. When the doubler is enabled, both the rising and
falling edges of REFIN become active edges at the PFD input.
RF Counter Reset
DB3 is the RF counter reset bit for the ADF4252. When this is
1, the RF synthesizer counters are held in reset. For normal
operation, this bit should be 0.
RF Charge Pump Three-State
This bit puts the charge pump into three-state mode when pro-
grammed to a 1. It should be set to 0 for normal operation.
When the doubler is enabled and lowest spur mode is chosen,
the in-band phase noise performance is sensitive to the REFIN
duty cycle. The phase noise degradation can be as much as 5 dB
for REFIN duty cycles outside a 45% to 55% range. The phase
noise is insensitive to REFIN duty cycle in the lowest noise mode
and in low noise and spur mode. The phase noise is insensitive
to REFIN duty cycle when the doubler is disabled.
RF Power-Down
DB5 on the ADF4252 provides the programmable power-down
mode. Setting this bit to a 1 will perform a power-down on both
the RF and IF sections. Setting this bit to 0 will return the RF
and IF sections to normal operation. While in software
power-down, the part will retain all information in its registers.
Only when supplies are removed will the register contents be lost.
4-Bit RF R Counter
The 4-bit RF R counter allows the input reference frequency
(REFIN) to be divided down to produce the reference clock to
the phase frequency detector (PFD). Division ratios from 1 to
15 are allowed.
When a power-down is activated, the following events occur:
1. All active RF dc current paths are removed.
2. The RF synthesizer counters are forced to their load state
conditions.
12-Bit Interpolator Modulus
This programmable register sets the fractional modulus. This is
the ratio of the PFD frequency to the channel step resolution on
the RF output.
3. The RF charge pump is forced into three-state mode.
4. The RF digital lock detect circuitry is reset.
5. The RFIN input is debiased.
6. The input register remains active and capable of loading and
latching data.
NOTES
1Wide-loop bandwidth is seen as a loop bandwidth greater than 1/10th of the
RFOUT channel step resolution (FRES).
2Narrow-loop bandwidth is seen as a loop bandwidth less than 1/10th of the
RFOUT channel step resolution (FRES).
REV. B
–21–
ADF4252
RF Phase Detector Polarity
Lock Detect
DB7 in the ADF4252 sets the RF phase detector polarity.
When the VCO characteristics are positive, this should be set to
1. When they are negative, it should be set to 0.
The digital lock detect output goes high if there are 40 successive
PFD cycles with an input error of less than 15 ns. It stays high
until a new channel is programmed or until the error at the PFD
input exceeds 30 ns for one or more cycles. If the loop bandwidth
is narrow compared to the PFD frequency, the error at the PFD
inputs may drop below 15 ns for 40 cycles around a cycle slip; thus
the digital lock detect may go falsely high for a short period until
the error again exceeds 30 ns. In this case the digital lock detect is
reliable only as a “loss of lock” indicator.
RF Charge Pump Current Setting
DB9 and DB10 set the RF charge pump current setting. This
should be set to whatever charge pump current the loop filter
has been designed with (see Table V).
RF Test Modes
These bits should be set to 0, 0, 0 for normal operation.
IF N DIVIDER REGISTER
(Address R4)
With R4[2, 1, 0] set to [1, 0, 0], the on-chip IF N divider register
will be programmed. Table VII shows the input data format for
programming this register.
MASTER REGISTER
(Address R3)
With R3[2, 1, 0] set to 0, 1, 1, the on-chip master register will be
programmed. Table VI shows the input data format for program-
ming the master register.
IF CP Gain
RF and IF Counter Reset
When set to 1, this bit changes the IF charge pump current
setting to its maximum value. When the bit is set to 0, the
charge pump current reverts back to its previous state.
DB3 is the counter reset bit for the ADF4252. When this is 1,
both the RF and IF R, INT, and MOD counters are held in reset.
For normal operation, this bit should be 0. Upon power-up, the
DB3 bit needs to be disabled, the INT counter resumes counting
in “close” alignment with the R counter. (The maximum error is
one prescaler cycle).
IF Prescaler
The dual-modulus prescaler (P/P + 1), along with the IF A and
B counters, determine the overall division ratio, N, to be realized
(N = PB + A) from the IFIN to the IF PFD input. Operating at
CML levels, it takes the clock from the IF input stage and divides it
down to a manageable frequency for the CMOS counters. It is
based on a synchronous 4/5 core. See Equation 2 and Table VII.
Charge Pump Three-State
This bit puts both the RF and IF charge pump into three-state
mode when programmed to a 1. It should be set to 0 for normal
operation.
IF B and A Counter
Power-Down
The IF A and B counters, in conjunction with the dual modulus
prescaler, make it possible to generate output frequencies that
are spaced only by the reference frequency (REFIN) divided
by R. The equation for the IFOUT VCO frequency is given in
Equation 2.
R3[3] on the ADF4252 provides the programmable power-down
mode. Setting this bit to a 1 will perform a power-down on both
the RF and IF sections. Setting this bit to 0 will return the RF
and IF sections to normal operation. While in software power-
down, the part will retain all information in its registers. Only
when supplies are removed will the register contents be lost.
IF R DIVIDER REGISTER
(Address R5)
When a power-down is activated, the following events occur:
1. All active dc current paths are removed.
With R5[2, 1, 0] set to [1, 0, 1], the on-chip IF R divider register
will be programmed. Table VIII shows the input data format for
programming this register.
2. The RF and IF counters are forced to their load state conditions.
3. The RF and IF charge pumps are forced into three-state mode.
4. The digital lock detect circuitry is reset.
IF REFIN Doubler
Setting this bit to 0 feeds the REFIN signal directly to the 15-bit
IF R counter. Setting this bit to 1 multiplies the REFIN
frequency by a factor of 2 before feeding into the 15-bit IF R
counter.
5. The RFIN input and IFIN input are debiased.
6. The oscillator input buffer circuitry is disabled.
7. The input register remains active and capable of loading and
latching data.
15-Bit IF R Counter
The 15-bit IF R counter allows the input reference frequency
(REFIN) to be divided down to produce the reference clock to
the IF phase frequency detector (PFD). Division ratios from
1 to 32767 are allowed.
XO Disable
Setting this bit to 1 disables the REFOUT circuitry. This will
be set to 1 when using an external TCXO, VCXO, or other
reference sources. This will be set to 0 when using the REFIN
and REFOUT pins to form an oscillator circuit.
IF CONTROL REGISTER
(Address R6)
With R6[2, 1, 0] set to [1, 1, 0], the on-chip IF control register
will be programmed. Table IX shows the input data format for
programming this register. Upon initialization, DB15–DB11
should all be set to 0.
MUXOUT Control
The on-chip multiplexer is controlled by R3[10–7] on the
ADF4252. Table VI shows the truth table.
If the user updates the RF control register or the IF control
register, the MUXOUT contents will be lost. To retrieve the
MUXOUT signal, the user must write to the master register.
–22–
REV. B
ADF4252
IF Counter Reset
delaying the resync activation until the locking transient is close
to its final frequency. In the IF R divider register, Bits R5[17–3]
are used to set a time interval from when the new channel is pro-
grammed to the time the resync is activated. Although the time
interval resolution available from the 15-bit IF R register is one
REFIN clock cycle, IF R should be programmed to be a value that
is an integer multiple of the programmed MOD value to set a
time interval that is at least as long as the RF PLL loop’s lock time.
DB3 is the IF counter reset bit for the ADF4252. When this is
1, the IF synthesizer counters are held in reset. For normal
operation, this bit should be 0.
IF Charge Pump Three-State
This bit puts the IF charge pump into three-state mode when pro-
grammed to a 1. It should be set to 0 for normal operation.
IF Power-Down
For example, if REFIN = 26 MHz, MOD = 130 to give 200 kHz
output steps (FRES), and the RF loop has a settling time of 150 µs,
then IF_R should be programmed to 3900, as
DB5 on the ADF4252 provides the programmable power-down
mode. Setting this bit to a 1 will perform a power-down on the IF
section. Setting this bit to 0 will return the section to normal
operation. While in software power-down, the part will retain all
information in its registers. Only when supplies are removed will
the register contents be lost.
26 MHz ×150 µs = 3900
Note that if it is required to use the IF synthesizer with phase
resync enabled on the RF synth, the IF synth must operate with
a PFD frequency of 26 MHz/3900. In an application where the
IF synth is not required, the user should ensure that Registers
R4 and R6 are not programmed so that the rest of the IF circuitry
remains in power-down.
When a power-down is activated, the following events occur:
1. All active IF dc current paths are removed.
2. The IF synthesizer counters are forced to their load state
conditions.
3. The IF charge pump is forced into three-state mode.
4. The IF digital lock detect circuitry is reset.
5. The IFIN input is debiased.
DEVICE PROGRAMMING AFTER INITIAL POWER-UP
After initially applying power to the supply pins, there are three
ways to operate the device.
RF and IF Synthesizers Operational
All registers must be written to when powering up both the RF
and IF synthesizer.
6. The input register remains active and capable of loading and
latching data.
IF Phase Detector Polarity
RF Synthesizer Operational, IF Power-Down
It is necessary to write only to Registers R3, R2, R1, and R0
when powering up the RF synthesizer only. The IF side will
remain in power-down until Registers R6, R5, R4, and R3 are
written to.
DB7 in the ADF4252 sets the IF phase detector polarity. When
the VCO characteristics are positive, this should be set to 1.
When they are negative, it should be set to 0.
IF Charge Pump Current Setting
DB8, DB9, and DB10 set the IF charge pump current setting.
This should be set to whatever charge pump current the loop
filter has been designed with (see Table VII).
IF Synthesizer Operational, RF Power-Down
It is necessary to write to only Registers R6, R5, R4, and R3 when
powering up the IF synthesizer only. The RF side will remain in
power-down until registers R3, R2, R1, and R0 are written to.
IF Test Modes
These bits should be set to [0, 0] for normal operation.
RF Synthesizer: An Example
The RF synthesizer should be programmed as follows:
RF Phase Resync
Setting the phase resync bits [15, 14, 11] to [1, 1, 1] enables
the phase resync feature. With a fractional modulus of M, a
fractional-N PLL can settle with any one of (2 ꢁ ꢂ)/M valid
phase offsets with respect to the reference input. This is different
to integer-N (where the RF output always settles to the same
static phase offset with respect to the input reference, which is
zero ideally) but does not matter in most applications where all
that is required is consistent frequency lock.
FRAC
RFOUT = INT +
× FPFD
(4)
MOD
where RFOUT = the RF frequency output, INT = the integer division
factor, FRAC = the fractionality, and MOD = the modulus.
1+ D
FPFD = REFIN
×
(5)
R
For applications where a consistent phase relationship between
the output and reference is required (i.e., digital beamforming),
the ADF4252 fractional-N synthesizer can be used with the phase
resync feature enabled. This ensures that if the user programs
the PLL to jump from Frequency (and Phase) A to Frequency
(and Phase) B and back again to Frequency A, the PLL will return
to the original phase (Phase A).
where REFIN = the reference frequency input, D = the RF
REFIN doubler bit, and R = the RF reference division factor.
For example, in a GSM 1800 system where 1.8 GHz RF frequency
output (RFOUT) is required, a 13 MHz reference frequency input
(REFIN) is available and a 200 kHz channel resolution (FRES) is
required on the RF output.
When enabled, it will activate every time the user programs
Register R0 or R1 to set a new output frequency. However if a
cycle slip occurs in the settling transient after the phase re-resync
operation, the phase resync will be lost. This can be avoided by
REF
IN
MOD =
FRES
13 MHz
MOD =
= 65
200 kHz
REV. B
–23–
ADF4252
So, from Equation 5:
For example, in an application that requires 1.75 GHz RF and
200 kHz channel step resolution, the system has a 13 MHz
reference signal.
1+ 0
1
FPFD = 13 MHz ×
= 13 MHz
One possible setup is feeding the 13 MHz directly to the PFD
and programming the modulus to divide by 65. This results in
the required 200 kHz resolution.
FRAC
65
1.8 GHz = 13 MHz × INT +
Another possible setup is using the reference doubler to create
26 MHz from the 13 MHz input signal. This 26 MHz is then
fed into the PFD. The modulus is now programmed to divide by
130, which also results in 200 kHz resolution. This offers supe-
rior phase noise performance over the previous setup.
where INT = 138 and FRAC = 30.
IF Synthesizer: An Example
The IF synthesizer should be programmed as follows:
IFOUT
=
P
×
B
+
A
×
FPFD
(6)
(
[
)
]
The programmable modulus is also very useful for multistandard
applications. If a dual-mode phone requires PDC and GSM1800
standards, the programmable modulus is a huge benefit. PDC
requires 25 kHz channel step resolution, whereas GSM1800
requires 200 kHz channel step resolution. A 13 MHz reference
signal could be fed directly to the PFD. The modulus would
then be programmed to 520 when in PDC mode (13 MHz /520 =
25 kHz). The modulus would be reprogrammed to 65 for
GSM1800 operation (13 MHz/65 = 200 kHz). It is important
that the PFD frequency remains constant (13 MHz). This allows
the user to design one loop filter that can be used in both setups
without any stability issues. It is the ratio of the RF frequency to
the PFD frequency that affects the loop design. Keeping this
relationship constant, and instead changing the modulus factor,
results in a stable filter.
where IFOUT = the output frequency of external voltage controlled
oscillator (VCO), P = the IF prescaler, B = the B counter value,
and A = the A counter value.
Equation 5 applies in this example as well.
For example, in a GSM1800 system, where 540 MHz IF fre-
quency output (IFOUT) is required, a 13 MHz reference frequency
input (REFIN) is available and a 200 kHz channel resolution
(FRES) is required on the IF output. The prescaler is set to 16/17.
IF REFIN doubler is disabled.
By Equation 5,
1+ 0
R
200 kHz = 13 MHz ×
if R = 65.
Spurious Optimization and Fastlock
By Equation 6,
As mentioned in the Noise and Spur Setting section, the part can
be optimized for spurious performance. However, in fastlocking
applications, the loop bandwidth needs to be wide. Therefore,
the filter does not provide much attenuation of the spurious. The
programmable charge pump can be used to avoid this issue. The
filter is designed for a narrow-loop bandwidth so that steady-state
spurious specifications are met. This is designed using the low-
est charge pump current setting. To implement fastlock during
a frequency jump, the charge pump current is set to the maxi-
mum setting for the duration of the jump. This has the effect of
widening the loop bandwidth, which improves lock time. When the
PLL has locked to the new frequency, the charge pump is again
programmed to the lowest charge pump current setting. This
will narrow the loop bandwidth to its original cutoff frequency
to allow for better attenuation of the spurious than the wide-loop
bandwidth.
540 MHz = 200 kHz × 16 × B + A
(
[
)
]
if B = 168 and A = 12.
Modulus
The choice of modulus (MOD) depends on the reference signal
(REFIN) available and the channel resolution (FRES) required at
the RF output. For example, a GSM system with 13 MHz
REFIN would set the modulus to 65. This means that the RF
output resolution (FRES) is the 200 kHz (13 MHz/65) necessary
for GSM.
Reference Doubler and Reference Divider
There is a reference doubler on-chip, which 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 will usually result in an improvement in noise
performance of 3 dB. It is important to note that the PFD can-
not be operated above 30 MHz due to a limitation in the speed
of the ꢃ-ꢄ circuit of the N divider.
Spurious Signals—Predicting Where They Will Appear
Just as in integer-N PLLs, spurs will appear at PFD frequency
offsets on either side of the carrier (and multiples of the PFD
frequency). In a fractional-N PLL, spurs will also appear at
frequencies equal to the RFOUT channel step resolution (FRES).
The ADF4252 uses a high order fractional interpolator engine,
which results in spurs also appearing at frequencies equal to
half of the channel step resolution. For example, examine the
GSM1800 setup with a 26 MHz PFD and 200 kHz resolution.
Spurs will appear at 26 MHz from the RF carrier (at an
extremely low level due to filtering). Also, there will be spurs at
200 kHz from the RF carrier. Due to the fractional interpolator
architecture used in the ADF4252, spurs will also appear at
12-Bit Programmable Modulus
Unlike most other fractional-N PLLs, the ADF4252 allows the
user to program the modulus over a 12-bit range. This means
that the user can set up the part in many different configurations
for a specific application, when combined with the reference
doubler and the 4-bit R counter.
–24–
REV. B
ADF4252
100 kHz from the RF carrier. Harmonics of all spurs mentioned
will also appear. With the lowest spur setting enabled, the spurs
will be attenuated into the noise floor.
byte has been written, the LE input should be brought high to
complete the transfer.
I/O port lines on the ADuC812 are also used to control power-
down (CE input) and to detect lock (MUXOUT configured as
lock detect and polled by the port input).
Prescaler
The prescaler limits the INT value. With P = 4/5, Nmin = 31.
With P = 8/9, Nmin = 91.
When operating in the mode described, the maximum SCLOCK
rate of the ADuC812 is 4 MHz. This means that the maximum
rate at which the output frequency can be changed will be 166 kHz.
The prescaler can also influence the phase noise performance.
If INT < 91, a prescaler of 4/5 should be used. For applications
where INT > 91, P = 8/9 should be used for optimum noise
performance.
Filter Design—ADIsimPLL
SCLK
DT
SCLK
A filter design and analysis program is available to help users
implement their PLL design. Visit www.analog.com/pll for a
free download of the ADIsimPLL software. The software
designs, simulates, and analyzes the entire PLL frequency
domain and time domain response. Various passive and active
filter architectures are allowed.
SDATA
TFS
LE
CE
I/O FLAGS
MUXOUT
(LOCK DETECT)
INTERFACING
ADSP-21xx
ADF4252
The ADF4252 has a simple SPI compatible serial interface for
writing to the device. SCLK, SDATA, and LE control the data
transfer. When LE (latch enable) goes high, the 24 bits that have
been clocked into the input register on each rising edge of SCLK
will be transferred to the appropriate latch. See Figure 1 for the
Timing Diagram and Table I for the Control Bit Truth Table.
Figure 9. ADSP-21xx to ADF4252 Interface
ADSP-2181 Interface
Figure 9 shows the interface between the ADF4252 and the
ADSP-21xx digital signal processor. Each latch of the ADF4252
needs (at most) a 24-bit word. The easiest way to accomplish this
using the ADSP-21xx family is to use the autobuffered transmit
mode of operation with alternate framing. This provides a means
for transmitting an entire block of serial data before an interrupt is
generated. Set up the word length for eight bits and use three memory
locations for each 24-bit word. To program each 24-bit latch, store
the three 8-bit bytes, enable the autobuffered mode, and then write
to the transmit register of the DSP. This last operation initiates the
autobuffer transfer.
The maximum allowable serial clock rate is 20 MHz, which
means that the maximum update rate possible for the device is
833 kHz or one update every 1.2 µs. This is certainly more than
adequate for systems that will have typical lock times in hun-
dreds of microseconds.
SCLOCK
MOSI
SCLK
SDATA
PCB DESIGN GUIDELINES FOR CHIP SCALE PACKAGE
The leads on the chip scale package (CP-24) are rectangular. The
printed circuit board pad for these should be 0.1 mm longer than
the package land length and 0.05 mm wider than the package land
width. The land should be centered on the pad. This will ensure
that the solder joint size is maximized.
LE
CE
I/O PORTS
MUXOUT
(LOCK DETECT)
ADuC812
ADF4252
The bottom of the chip scale package has a central thermal pad.
The thermal pad on the printed circuit board should be at least
as large as this exposed pad. On the printed circuit board, there
should be a clearance of at least 0.25 mm between the thermal
pad and the inner edges of the pad pattern. This will ensure that
shorting is avoided.
Figure 8. ADuC812 to ADF4252 Interface
ADuC812 Interface
Figure 8 shows the interface between the ADF4252 and the
ADuC812 microconverter. Since the ADuC812 is based on
an 8051 core, this interface can be used with any 8051 based
microcontroller. The microconverter is set up for SPI master
mode with CPHA = 0. To initiate the operation, the I/O port
driving LE is brought low. Each latch of the ADF4252 needs
(at most) a 24-bit word. This is accomplished by writing three
8-bit bytes from the microconverter to the device. When the third
Thermal vias may be used on the printed circuit board thermal pad
to improve thermal performance of the package. If vias are used,
they should be incorporated in the thermal pad at 1.2 mm pitch
grid. The via diameter should be between 0.3 mm and 0.33 mm,
and the via barrel should be plated with 1 oz copper to plug the via.
The user should connect the printed circuit board to AGND
.
REV. B
–25–
ADF4252
V
VVCO
V
V
VVCO
DD
P
P
R48
0ꢁ
R49
0ꢁ
R1
20ꢁ
R44
0ꢁ
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
VDD’
C9
22ꢂF
C11
22ꢂF
C5
22ꢂF
C29
22ꢂF
C7
22ꢂF
C3
22ꢂF
R43
0ꢁ
IF
J6
RF
OUT
J7
OUT
C8
10pF
C10
10pF
C12
10pF
C6
10pF
C30
10pF
C4
10pF
C15
C27
100pF
100pF
14
VCC
RF
14
VCC
V 1
V 2
P
P
R12
18ꢁ
R22
18ꢁ
R17
R20
13kꢁ
470ꢁ
2
2
V
IN
10
10
RF
OUT
V
CP
CP
RF
IN
OUT
IF
R13
C16
R21
18ꢁ
R23
18ꢁ
C26
100pF
C20
82pF
C19
C18
270pF
C23
10nF
C24
C25
3.3nF
18ꢁ
VCO2
VCO190–540T
VCO1
VCO190–1730T
100pF
U1
2.2nF
100nF
R14
18ꢁ
ADF4252BCP
R16
7.5kꢁ
R19
270ꢁ
CP
1
R15
51ꢁ
R24
51ꢁ
GND
RF
A
B
IF
A
IN
IN
C17
C28
100pF
REF
J5
100pF
IN
RF
IN
T13
C13
1nF
C14
1nF
C43
C44
100pF
T16
100pF
R27
10kꢁ
R28
10kꢁ
5V
3V
MUXOUT
V
R45
0ꢁ
R27
2.7kꢁ
DD
R47
0ꢁ
R11
51ꢁ
R29
10kꢁ
A
1
GND
3
D
LE
R46
0ꢁ
GND
O/P
Y3
D4
DATA
CLK
A
2
2
GND
4
B+
GND
CP
2
GND
C46
22ꢂF
C45
10pF
T14
C32
33pF
Y2
10MHz
R26
1kꢁ
R39
0ꢁ
R4
1Mꢁ
C31
33pF
REF
J8
OUT
1
4
U6
2
R38
0ꢁ
VCC
3V
5V
R34
0ꢁ
R35
0ꢁ
Figure 10. Typical PLL Circuit Schematic
–26–
REV. B
ADF4252
OUTLINE DIMENSIONS
24-Lead Lead Frame Chip Scale Package [LFCSP]
(CP-24)
Dimensions shown in millimeters
0.60 MAX
4.0
BSC SQ
PIN 1
INDICATOR
0.60 MAX
1
19
18
24
PIN 1
0.50
BSC
2.25
2.10
1.95
INDICATOR
3.75
TOP
SQ
BOTTOM
VIEW
VIEW
BSC SQ
0.50
0.40
0.30
6
13
12
7
0.25 MIN
2.50 REF
0.80 MAX
0.65TYP
1.00
0.85
0.80
12ꢃ MAX
0.05 MAX
0.02 NOM
0.30
0.23
0.18
COPLANARITY
0.20 REF
0.08
SEATING
PLANE
COMPLIANTTO JEDEC STANDARDS MO-220-VGGD-2
REV. B
–27–
ADF4252
Revision History
Location
Page
10/03—Data Sheet changed from REV. A to REV. B.
Change to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Change to TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Change to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Change to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Inserted Lock Detect section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Change to OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
–28–
REV. B
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