Capacitance coupled isolation amplifier and method

摘要

An isolation amplifier includes an electrically floating comparator having inputs coupled to inputs of the isolation amplifier. Operating power is supplied to the isolation amplifier by an electrically floating rectifier circuit. A triangular waveform generator produces a triangular output signal which is combined by means of a first coupling capacitor with a differential input signal applied to the inputs of the isolation amplifier. A second coupling capacitor couples the triangular waveform to the floating rectifier circuit. The floating comparator circuit produces a pulse width modulated output signal representative of the magnitude of the differential input signal. A demodulator circuit inverts the pulse width modulated signal to an analog output signal which is an amplified replica of the differential input signal. The analog output signal is electrically isolated from the differential input signal.