Question about NRF5340 PDM GAIN signal attenuation

[David Duan]

Hi DevZone,

My customer found that when using the NRF5340 PDM, there is significant attenuation if the incoming audio signal is a 2kHz signal.

Upon checking the specifications, I noticed that the PDM has a decimation filter with GAINL and GAINR registers.

Is it possible to adjust the GAIN values of these registers to reduce the level of signal attenuation?

[Michal]

Yes, as shown in the datasheet:

https://docs.nordicsemi.com/bundle/ps_nrf5340/page/pdm.html#ariaid-title5

https://docs.nordicsemi.com/bundle/ps_nrf5340/page/pdm.html#ariaid-title26

It is possible to set up up to +20 dB gain adjustment in the decimation filter.

Best regards,

Michal