Datasheet

AD9511
Rev. A | Page 27 of 60
PLL WITH EXTERNAL VCO AND BAND-PASS
FILTER FOLLOWED BY CLOCK DISTRIBUTION
An external band-pass filter may be used to try to improve the
phase noise and spurious characteristics of the PLL output. This
option is most appropriate to optimize cost by choosing a less
expensive VCO combined with a moderately priced filter. Note
that the BPF is shown outside of the VCO-to-N divider path,
with the BP filter outputs routed to CLK1. Some power can be
saved by shutting off unused functions, as well as by powering
down any unused clock channels (see the
Register Map and
Description
section).
05286-012
R
N
PFD
STATUS
CHARGE
PUMP
LVPECL
DIVIDE
LVPECL
DIVIDE
LVPECL
DIVIDE
LVDS/CMOS
DIVIDE
LVDS/CMOS
DIVIDE
Δ T
FUNCTION
V
REF
AD9511
PLL
REF
CLK1 CLK2
REFERENCE
INPUT
REFIN
LOOP
FILTER
VCO
BPF
CLOCK
OUTPUTS
SERIAL
PORT
Figure 32. AD9511 with VCO and BPF Filter