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MITSUBISHI SOUND PROCESSOR ICs
M65845AFP
DIGITAL ECHO WITH MICROPHONE MIXING CIRCUIT
3 Input and output LPF
Signal through frequency fsig is also determined by LPF of Digital Echo cut off frequency.
2 degree LPF of Digital Echo is formed by external resistance and capacitor .
(refer to next figure) So, cut off frequency is determined by next formula.
fsig=
2π
1
R8 • R9 • C13 • C14
LPF1
REF
LPF2
REF
12
13
23
24
R7
24kΩ
R8
C14
24kΩ
R9 24kΩ
R7
24kΩ
R8
C14
24kΩ
R9 24kΩ
C13
C13
MITSUBISHI
ELECTRIC
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