I am designing a preamp intended to interface with a microphone in common headphones (e.g. apple earpods, or sony headphones with a microphone) which will then connect to my ADC's inputs.
I've developed a circuit based on a reference design, however the reference does not take into account the need to bias the microphone. From what I gather, I need to provide ~1.65V to the mic.
My circuit is using an AC voltage source @ 4mVrms to simulate output from the microphone (not sure if that's a fair model) and I'm not including any mic resistance.
- How would I bias this mic? providing power to net 8 does not show a bias (in simulation).
- How do I ensure the gain of this pre-amp is correct? Finding datasheets for the mic in apple earpods is next to impossible so I don't have any real specs to go from.
- Are there any reference designs that perform the same task?