PDM signal introduction

AN3998

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Doc ID 022391 Rev 1

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PDM signal introduction

Pulse density modulation, or PDM, is a form of modulation used to represent an analog

signal in the digital domain.

In a PDM signal, specific amplitude values are not encoded into pulses as they would be in

PCM. Instead it is the relative density of the pulses that corresponds to the analog signal's

amplitude.

To get the framed data from the PDM bit stream, decimation filters are usually used. The

first stage of decimation is used to reduce the sampling frequency, followed by a high pass

filter to remove the signal DC offset.