A novel differential synchronous demodulator for AC signals

摘要

We describe a new analog differential synchronous demodulator forAC signals where: (i) the signal is synchronously demodulated using thefloating capacitor technique after being amplified, if necessary, by alow-gain AC amplifier with differential input and differential output,thus yielding a very high CMRR; and (ii) the differential-to-singleended signal conversion is performed after demodulation, that is, on alow-frequency signal that can be amplified by low-cost, high-performancecircuits. We prevent the possible signal-to-noise ratio degradationbecause of synchronous sampling by using bandpass differential filters