AK2346B Datasheet, PDF (26/31 Pages) Asahi Kasei Microsystems – Two-way Radio Audio Processor

ASAHI KASEI
[AK2346B]
16. Recommended External Application Circuits
1) TXA1 Amplifier
This is an operational amplifier required for typical transmit microphone. The gain should be less
than 30dB. To eliminate high frequency noise component over than 100kHz from input signal,
please compose 1^st or 2^nd order anti-aliasing filter. The following simplified schematic shows an
example of 2^nd order anti-aliasing filter that has 30dB gain and 10kHz cut-off frequency.
_
+
TXA1
4 TXINO
C2
R3
R1 C1
3 TXIN _R2
C3
AGND
C1=0.47uF
C2=33pF
C3=2200pF
R1=R2=10kΩ
R3=330kΩ
LSI
2) EXTLIMIN pin configuration
To eliminate an external DC offset must be decoupled by capacitor to signal input.
6 EXTLIMIN
C
C=0.047uF
LSI
3) RXA1 Amplifier
This is an operational amplifier suitable for receive gain adjuster and anti-aliasing filter to
eliminate high frequency noise component over 100kHz The gain should be less than 20dB.
The following simplified schematic shows an example of 2^nd order anti-aliasing filter that has
20dB gain and 39kHz cut-off frequency.
_
+
RXA1
22 RXINO
C2
R3
R1 C1
23 RXIN _R2
C3
AGND
C1=0.47uF
C2=33pF
C3=560pF
R1=10kΩ
R2=9.1kΩ
R3=100kΩ
MS1409-E-00
LSI
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2012/05