CMX991 Datasheet, PDF (16/56 Pages) CML Microcircuits – Two-mode demodulator

RF Quadrature Transceiver / RF Quadrature Receiver
CMX991/CMX992
TXIP
I Inputs
TXIN
CMX991
IF LO _90°
+
TXIFOUT ^C1
TXQP
Q Inputs
TXQN
TXIF Filter
I/Q Modulator
Output
Figure 11 Example External Components – I/Q Modulator Output
C1 1nF
Table 9 I/Q Modulator Output Matching Components
4.4 Main Local Oscillator
4.4.1 Receiver LO Input (CMX991 and CMX992)
The main local oscillator input is differential, but the normal configuration will be single ended, with the
other input ac coupled to ground as shown in Figure 12. To prevent signals present on the local ground
affecting the LO, the ground associated with capacitor C2 should be the same ground that is used for the
LO source. In this way any ground noise will be common mode at the inputs A and B and will be rejected.
LO Input
C1
A
CMX991
CMX992
Divider
B
C2
A = MIXLOP
B = MIXLON
Figure 12 Example External Components – Rx LO Input
C1 1nF
C2 1nF
Table 10 Rx LO Input Components
 2015 CML Microsystems Plc
16
D/991_992/20