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Choosing a good opamp for a mic preamp

Question asked by JeradL on Jul 6, 2011
Latest reply on Oct 9, 2012 by JeradL

I'm looking for recommendations for a good opeamp to use in a simple microphone preamp circuit for ADI's MEMS microphones. The noise floor of these microphones is at -100 dBV (10 uV), A-weighted, with a 20 kHz bandwidth. The typical use of this preamp will apply between about 12-36 dB of gain, depending on the application. An example of a typical implementation of this non-inverting circuit is shown in Figure 8 of the ADMP404 datasheet.

 

Of course, the AD797 is a great audio opamp, but this may be overkill for some applications. I have used the OP275 and AD8606 in audio designs, but I've been looking at other opamps as well. The noise, distortion, and slew rate specs of the AD8597, ADA4841 (replacement for the OP275?), and ADA4075 (recommended in this thread) look good. Are there any good choices I'm missing here, or other specs I should be thinking of?

 

The MEMS microphone datasheets currently show an OP177 in a preamp circuit. Is this a good choice, or would another device be better as a general, standard recommendation?

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