Electrical – Negative Voltage Reference For Instrumentation Amplifer


I'm trying to measure a variable resistance, RX, creating an AC voltage with two PWM and applying it to a wheatstone bridge. The PWM goes from 0 to 3.3v and to measure the voltage differential i'm connecting each arm to a InAmp to read after with a ADC. My problem is that my circuit is unipolar (+3.3v) so i'm looking for solutions to create an negative voltage source (-3.3v) to power the opamp in the negative rail to avoid saturation. I read about charge pumps, is there any other better solution ?

Thank you in Advance.

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Best Answer

Why you are looking for a "better solution" over already excellent solutions that industry already has invented? In situations like yours I use LM2776. It just mirrors your positive supply. The results are excellent: small PCB footprint, minimal number of passives, easy to get clean voltage.