adf4207 Analog Devices, Inc., adf4207 Datasheet - Page 10

• Manufacturer Part Number: adf4207
• Description: Dual Rf Pll Frequency Synthesizers
• Manufacturer: Analog Devices, Inc.

ADF4206/ADF4207/ADF4208
The PFD includes a delay element which sets the width of the
antibacklash phase. The typical value for this is in the ADF4206
family is 3 ns. The pulse ensures that there is no deadzone in
the PFD transfer function and minimizes phase noise and refer-
ence spurs.
MUXOUT AND LOCK DETECT
The output multiplexer on the ADF4206 family allows the
user to access various internal points on the chip. The state
of MUXOUT is controlled by P3, P4, P11, and P12. See
Tables III and V. Figure 6 shows the MUXOUT section in
block diagram form.
CP OUTPUT
R DIVIDER
N DIVIDER
R DIVIDER
N DIVIDER
HI
HI
D1
D2
CLR1
CLR2
U1
U2
Q1
Q2
UP
DOWN
ELEMENT
DELAY
U3
CPGND
V
P
CHARGE
PUMP
CP
Lock Detect
MUXOUT can be programmed for analog lock detect. 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 it is high with narrow low-going pulses.
INPUT SHIFT REGISTER
The functional block diagram for the ADF4206 family is shown
on Page 1. The main blocks include a 22-bit input shift register,
a 14-bit R counter, and an 17-bit N counter, comprising a 6-bit
A counter and an 11-bit B counter. Data is clocked into the 22-bit
shift register on each rising edge of CLK. The data is clocked
in MSB first. Data is transferred from the shift register to one of
four latches on the rising edge of LE. The destination latch is
determined by the state of the two control bits (C2, C1) in the
shift register. These are the two LSBs DB1, DB0, as shown in
the timing diagram of Figure 1. The truth table for these bits is
shown in Table I.
RF2/RF1 ANALOG LOCK DETECT
Control Bits
C2
0
0
1
1
RF2 ANALOG LOCK DETECT
RF1 ANALOG LOCK DETECT
RF2 R COUNTER OUTPUT
RF2 N COUNTER OUTPUT
RF1 R COUNTER OUTPUT
RF1 N COUNTER OUTPUT
C1
0
1
0
1
Table I. C2, C1 Truth Table
Data Latch
RF2 R Counter
RF2 AB Counter (and Prescaler Select)
RF1 R Counter
RF1 AB Counter (and Prescaler Select)
MUX
CONTROL
DV
DGND
DD
MUXOUT