CMX972 Datasheet, PDF (18/41 Pages) CML Microcircuits – Small 32-lead VQFN Package

Quadrature Demodulator with IF PLL/VCO
CMX972
where
f_out = The desired output frequency in MHz
f_ref = The reference frequency supplied to the PLL on pin REFIN in MHz
M = Divider value programmed in the M divider register (see section 6.6.1)
R = Divider value programmed in the R divider register (see section 6.7.1)
also note that f_comparision = f_ref / R
The PLL only supports VCOs with a positive tuning slope, i.e. a high tuning voltage from DO results in a
higher oscillation frequency from the VCO.
NR
Control
VCO
NR
Amplifier
RXLO Input Pin and
Demodulator LO drive
CMX972
Switching
M Divider
(Feedback)
80 - 32767
R Divider
(Reference)
2 - 8191
REFIN
VCO
Output
Buffer
Phase
Detector
Lock
Detect
VCO
Tank &
Varactors
Figure 12 PLL Architecture
 2015 CML Microsystems Plc
18
D/972/2