A high voltage AC measurement method and circuit is disclosed to measure with zero offset and mirrored distortion based on hybrid chopping and fully differential signal path. There is a scheme with hybrid chopping and dual mixed signal paths. It applies high frequency chopping to the voltage measurement signal before the low-voltage signal conditioning, then samples and converts it to digital with two simultaneous ADCs, and finally demodulate the chopped signal by software. This technique not only reduces DC errors and drift but also cancels the distortion asymmetry caused by ADC non-linearity. The resultant DC accuracy and resolution can be significantly smaller than 1 LSB.
