Cirrus Logic CRD5378 - Manual (Page 15)

CRD5378
DS639RD2 15
2.2.1.6 Common Mode Bias
Differential analog signals into the CS3301A/02A amplifiers are required to be biased to the center of the
power supply voltage range, which for bipolar supplies is near ground potential. Resistors to create the
common mode bias are selected based on the sensor impedance and may need to be modified from the
CRD5378 defaults depending on the sensor to be used. Refer to the recommended operating bias con-
ditions for the selected sensor, which are available from the sensor manufacturer.
Land Common Mode Filter Specification Value
Common Mode Capacitance 10 nF + 10%
Common Mode Resistance 200
Ω
Common Mode -3 dB Corner @ 6 dB/octave 80 kHz + 10%
Land Differential Filter Specification
Value
Differential Capacitance 10 nF + 10%
Differential Resistance 200
Ω + 200 Ω = 400 Ω
Differential -3 dB Corner @ 6 dB/octave 40 kHz + 10%
Marine Common Mode Filter Specification Value
Hydrophone Group Capacitance 128 nF + 10%
Differential Resistance 412 k
Ω + 2 kΩ
-3 dB Corner @ 6 dB/octave 3 Hz + 10%
Specification Value
Geophone Sensor Bias Resistance
20 k
Ω || 20 kΩ = 10 kΩ
Hydrophone Sensor Bias Resistance 18 M
Ω || 18 MΩ = 9 MΩ