User guide

CM52 Integrators’ Manual
WI_DEV_CM52_UGD_001-001
Page 44 of 53
CM52 Integrators’ Manual
3.4 Analog Audio Group Recommended Circuitry
3.4.1 Creating an analog ground
An analog ground plane should be generated which connects to GND in one point so that high
frequency digital current is not floating through the analog ground. Connecting the analog ground
in only one point avoids ground currents from power supplies and other high current circuitry from
creating noise in the analog circuitry. This common point should be located where the analog
supply voltage (VANA) is generated (at filter (A), or regulator (B) depending on implementation).
5V
VANA
12V
VANA
Regulator
BA
Figure 25: Creating an analog reference voltage (BIAS)
The BIAS reference should be generated from the analog supply voltage (VANA) and be referenced
to the analog ground. This reference shall be used to bias all analog circuitry in the application.
-
+
0
100k
100k
VANA
BIAS
Figure 26: BIAS/VANA Reference
The bias can be tapped directly from the resistor voltage divider, but the amplifier will make the
bias more stable and less susceptible to noise.
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