Given that the original post is a year old, I suspect we won't get an answer.
He did say that he split the analog and digital ground planes per the datasheet, and that is possibly his problem. (Why app notes continue to push the discredited plane…
Hello,
Thank Chris very much for pointing out the correct feedback gain using INA331.
Thank Collin very much for suggesting OPA1611, INA217, INA163 or INA103.
However, the input decoupling capacitor(1uF) cannot be removed because there will be 3 mic signals…
Hello Hao,
Almost always, power and noise performance tend to be trade-offs of one another.
For best noise-performance, you might consider the INA163 or INA217 (~1nV/rt(Hz) each). However, the typical quiescent current for these devices is close to 10mA…
Hi Adrian,
Having an asymetrical voltage wouldn't affect the INA217 very much. As long as your signal stays within the allowed input voltage range of the device. And here is were I see and issue for your application: The input range for the INA217 goes…
Shelly,
This is not the correct forum for audio ADCs and DACs. However, the amplifiers that are specifically intended for microphone pre-amplifier use are the: INA217, INA163, INA166, and the older INA103. The typical microphone pre-amplifier circuit…
Hi,
I selected INA217 for the microphone signal amplification as it offers low noise.
I need to know if there is any document explaining its operation when input pin 2 and 3 contains an audio signal from knowles NR 3158 microphone +ve and -ve terminals…
David,
As was the case of INA217, you MUST always provide a DC bias to the input terminals; therefore, you may not capacitively coupled the non-inverting input as shown in your schematic - this would cause a charge built up across the input cap (due to…
1282634,
The 1k resistor on the inverting input will help reduce the offset voltage due to input bias current. The INA217 is a very low noise amplifier. It very low noise is important in your circuit, you might benefit by reducing this resistance to a…
I have another question, this knowles mic has a high impedance how does that affect my choice of the opamp? I used INA217 before and it didn't work, the IC gets too hot.
Let me answer the question about AC-coupling Rgain (Rg) first.
I'm surprised that neither the INA163 or INA217 datasheets mention the fact that a capacitor can be placed in series with Rg to limit DC gain. Depending on the gain and the resulting Rg value…
