CMX972 Datasheet, PDF (27/41 Pages) CML Microcircuits – Small 32-lead VQFN Package

Quadrature Demodulator with IF PLL/VCO
CMX972
VCO Control Register b7 – b2
These bits allow the user to adjust the intermodulation performance of the Rx I/Q mixers. The
default value is ‘0’ for all the bits. Improved intermodulation can be achieved with a particular value
in these bits. The recommended value for optimum performance is ‘111111’. This value does not
vary between devices or with frequency. For further details see section 7.2.
VCO Control Register b1 – b0
VCO amplifier Negative Resistance (NR) control for optimum phase noise performance, see
section 5.3.2.2.
Bit: b2 b1
0 0 NR maximum (highest Q tank circuit)
0 1 NR Intermediate value
1 0 NR Intermediate value
1 1 NR minimum (lowest Q tank circuit)
6.8.2 VCO Control Register - $DF: 8-bit read
This register reads the value in register $2F, see section 6.8.1 for details of bit functions.
 2015 CML Microsystems Plc
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