CMX971 Datasheet, PDF (16/25 Pages) CML Microcircuits – Small 16-lead VQFN Package

Quadrature Modulator
CMX971
2
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
-3
10
100
Frequency / MHz
Figure 7 Typical Variation in Modulator Output Level with Frequency
1000
8.2.1 Quadrature Accuracy
The modulation accuracy is excellent and consistent with frequency. The I/Q phase and amplitude balance
can be measured as a combined result in terms of image suppression when sine and cosine waves are
applied to the I and Q channels. Typical results for 7kHz I/Q signals are shown in Figure 8.
The CMX971 can be used to generate a wide range of modulations including those with stringent adjacent
channel requirements, for example C4FM modulation for the APCO P25 system – see Figure 9. In this
figure, the I/Q input level was 700mVp-p and the measured adjacent channel power is -70dB.
 2015 CML Microsystems Plc
16
D/971/4