Analog Devices AD9864, User Manual

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The LO input for the
’s mixer can be supplied by
either an external RF generator via SMA connector J1, or one
of two VCO options on the PCB as shown in figure 4. The
two VCO options include a low power MAX2606 series or
To optimize the loop
filter, the VCO’s K
VCO
can be determined by driving a DC
voltage into TP2 while monitoring the VCO output frequency.
a standard footprint and can
be replaced by other vendor models like ZCOM, and RFMD.
In addition, the MAX2606 VCO requires an high Q external
inductor, L4, that sets its tuning frequency range and is also
part of a product family providing other frequency ranges.
The loop filter consists of R35, C39 and
C40 with R31 and R32 being used to select between the VCO
inputs. Note that these resistors also form an additional pole
for the loop filter when combined with C58 and C37
respectively. The selection of the LO options is via the
installation/removal of 0 ohm resistors as shown in Table II.
Table I. Selection of LO options