Overview

The LA8638V provides dynamic range expansion, noise suppression for enhancing the quality of audio signals in cordless telephones and other communications systems. This single chip provides the functions that make it ideal for cordless telephones: a compressor with a logarithmic compression ratio of 1/2, expander with a logarithmic expansion ratio of 2, splatter filter, microphone amplifier, BTL amplifier, waveform shaper for the receiving signal, muting for both receiving and transmitting signals, and standby operation.

Features

• Full processing of baseband signals for both receiving and transmitting signals

• Built-in BTL receiver amplifier for driving a ceramic speaker with a load of 2 kΩ

• Standby operation that conserves battery power during intermittent reception by disabling all but the waveform shaper for the receiving signal

• Built-in splatter filter with user-specified fc

• Low-voltage operation (1.8 V to 5.5 V)

Functions

• Transmitter circuits: compressor, microphone amplifier, limiter (IDC), muting, output level changes to userspecified levels, and splatter filter

• Receiver circuits: expander, buffer amplifier for filters, muting, output level changes to user-specified levels, and BTL amplifier

• Other circuits: waveform shaper for the receiving signal and standby operation