UG-383 Datasheet, PDF (4/16 Pages) Analog Devices – Self-contained board, including synthesizer

UG-383
EV-ADF4159EB1Z/EV-ADF4159EB3Z User Guide
LOOP FILTER
The loop filter schematic is included in Figure 13. The general
placement of loop filter components is shown in Figure 3. When
using a loop filter, calculate the values of the necessary com-
ponents and solder them to the board. The ADIsimPLL software,
which is available on the CD included in the evaluation board kit or
from www.analog.com/adisimpll, provides tools for designing loop
filters and calculating component values.
After soldering the loop filter components to the evaluation board,
connect a 15 V supply to the op amp power supplies, a 15 V supply
to the red 15 V test point, and the ground to the black AGND
test point (see Figure 1). See the Sample Loop Filter section for
an example configuration.
C1
R1
R2
C3
C2
OP AMP
Sample Loop Filter
Use the parameters of the sample loop filter described in this
section as a guide for adding a loop filter onto the evaluation
board.
Refer to Figure 3 for proper placement of components and to
Table 1 for recommended component values.
The sample loop filter is designed for
• VCO kV = 150 MHz/V
• PFD frequency = 100 MHz
• Charge pump current = 2.5 mA
• Loop bandwidth = 282 kHz
• Phase margin = 48.1°
Table 1. Sample Loop Filter Components Values
Component
Value
R1
100 Ω
C1
220 pF
R2
360 Ω
C2
5.6 nF
R3
1 kΩ
C3
180 pF
C4
180 pF
R3
C4
Figure 3. Placement of Loop Filter Components
Rev. B | Page 4 of 16