Hi ! all,
how to reduce white noise of ADMP441? thank you for all replies!
In your block diagram, I assume that your ADC is actually a DAC, right? Which DAC are you using for your test setup?
You also show that the analog output from the DAC is connected through an amplifier to the input of your PC. Is this using the PC's built-in sound card? These sound cards are usually very noisy; the noise floor of the analog audio input on the PC is almost certainly higher than the noise floor of the ADMP441 microphone.
Is the noise in the files that you sent what you're hearing in the right or the left channel? If it's the right channel, then that is not microphone noise. The right channel will just output whatever noise is output from the DAC's right channel. If you pull the ADMP441's L/R pin high, then you will hear the microphone audio in the right channel and you will hear this same noise now in the left channel.
What white noise are you hearing from the ADMP441? This microphone has an equivalent input noise of 33 dB SPL (61 dB SNR), so the noise floor in the digital output will be at -87 dBFS. There is not way to reduce the noise level of this microphone beyond that; this is the limit of this mic's noise performance.
Does this answer your question?
Thanks! that would be the background niose of ADMP441 as you mentioned. two attached files show the noise, the other is block diagram.
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