Cordless telephone voice processing circuit diagram

Both mobile phones and desktop computers of the CX9800 model use high-performance voice processing circuits to compress the amplitude and bandwidth of the microphone signal, improving the sensitivity of the microphone and the adaptability of the microphone to distance. The first stage is a limiting amplifier, and the second stage is an active filter. A high-pass RC filter is inserted between the microphone and the amplifier to pre-emphasize the amplifier input signal; in the receiving circuit, de-emphasis is performed in the frequency identification output circuit to improve the signal-to-noise ratio of the voice signal. The mobile phone amplifier uses 4558, and the desktop computer uses two single op amp circuits, model 741.