I am trying to design an op-amp input stage to capture a guitar through an ADC, specifically the ADC on an Arduino Due (3.3V, 12 bit). I am aware there are numerous ways to configure and bias the op-amps. I have designed a simple circuit based on a inverting amp followed by an active LP filter. The system will be running off a 9V battery and the power will be provided to the op-amps and uC (regulated) from this.
The aim being:
- Bias the signal around Vdd/2 (mid of ADC input range)
- Amplify the signal to use best of the ADC's range
- Lowpass filter the input signal at Nyquist rate (fs/2) to avoid aliasing
However, I have been unable to find much information on what the benefits or drawbacks of different configurations and methods of biasing are, specifically for this kind of signal. I have not yet measured the voltage output of my guitar so the specifics of the required gain properties are not known yet! Aslo, will I require a high input impedance for a guitar?
Any advice or comments would be greatly appreciated.