Analog Devices has both PDM output and I2S digital MEMS microphones. What are the differences between these?
A PDM output microphone, like the ADMP421, has a high-sample rate pulse density modulated (PDM) digital output. The data output from these microphones is typically input to a codec with a PDM input, like the ADAU1761. The codec decimates the data down to a lower sample rate, such as 48 kHz, for processing.
An I2S microphone includes the decimation filters, so its output is at a "typical" audio sample rate (48 kHz) and can digitally connect directly to a DSP or other processor. With an I2S microphone, like the ADMP441, a codec or ADC is not needed.
I have just written an article with additional details on the differences, advantages, and disadvantages of these different digital audio formats. You can find the article here: Common Inter-IC Digital Interfaces for Audio Data Transfer (pdf link).
Retrieving data ...