Cirrus Logic CDB5376 - Manual (Page 18)

CDB5376
18 DS612DB3
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. This common mode bias
voltage is created by buffering the voltage reference, which is nominally +2.5 V relative to the VA- power
supply.
Resistors to create the common mode bias are selected based on the sensor impedance and may need
to be modified from the CDB5376 defaults depending on the sensor to be used. Refer to the recommend-
ed operating bias conditions 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 Differential Filter Specification Value
Hydrophone Group Capacitance 128 nF + 10%
Differential Resistance 412 k
Ω + 2 kΩ = 400 Ω
-3 dB Corner @ 6 dB/octave 40 kHz + 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