Audio Codec is a chip used in embedded applications which can receive Analog data and at the same time provide Analog data output. Audio Codec converts the Analog Data to Digital Data and vice versa. So, Audio Codec basically has an Analog to digital converter (ADC) and Digital to analog converter (DAC) integrated. Why we need to do this analog to digital conversion and from digital to analog again? This has many advantages, one simple case is that after converting the incoming analog signals to digital signals, the digital signals can be processed further by the processor to improve the sound quality. Take the simple case of a sound system, where it has a MIC and Speaker are attached. When we speak, MIC outputs Analog data and this shall be provided to a Audio Codec which converts it to digital data and then collect digital data from host processor to output analog data to speaker.
Audio CODEC with PGA:
Some of the Audio Codes do have PGA as the first stage at the analog input. PGA shall be programmable to adjust the gain and hence amplify low level audio signals before providing input to the ADC. PCM3052A is an example CODEC which has PGA along with LPF as the first stage.
Audio CODEC without PGA:
AD1938 is an audio codec which does not have the PGA.
Audio codec has to interface to the host processor. The interface is categorized into two:
- interface for transferring the Digital data to the processor
- interface to configure the registers of the audio codec
The digital data transfer between the processor and the audio codec happens using:
- I2S
- TDM
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