need to use the bias voltage for the differential inputs adau1761?
I am designing a mic mixer project that will be connected to the output from a wireless recieved (balanced xlr). do i need the circuitry used o the evaluation board, and do i need to use the BIAS voltage? my guess is that the bias voltage is for when a passive mic is used. I am thinking that the output from the wireless mic reciever is already to input if capacitor coupled . Should i connect the + and - each through a 10k resistor , then a 10uf cap into the Neg pos inputs?
Audio Signal Processors
differential_input
mic_bias
SigmaDSP Audio Processors
adau1761
Hi Paul,
Welcome to the forum. Sorry for the long response time. I've been going full steam on a very urgent PCB design that I just finished up yesterday, and while that project was underway I unfortunately didn't have much time to spend on forum and support issues.
If you have a signal that is actively driving the differential inputs, then you're correct; MICBIAS does not need to be used. It is used in cases where a passive mic is connected so it can provide a reference voltage. CM is used for the same purpose, but in cases where no current needs to be drawn (MICBIAS is actually capable of sourcing some current).
The 10 uF capacitor will AC-couple the differential signals so that they are centered around AVDD/2. I'm not sure if the 10k resistor is required or not.
Have you tried this on our evaluation board? You can easily disconnect the MICBIAS from the differential inputs by disconnecting J15 and J18.
Thank You. I wanted to be sure, asking the experts. I will try it on the EVAL b oard first, thanks for the tip
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