Patent ID: 6812666
Filing Date: 2004-11-02
Classification: G05B,H03M

Abstract:
A circuit for recovering an input signal having a PWM frequency and having a first potential which is offset by a common mode displacement from a second potential, comprising:circuitry for converting the input signal at said first potential to a pulse width modulated signal; and two level shifting circuits for level shifting rising edges and falling edges, respectively, of said pulse width modulated signal from said first potential to said second potential; wherein the circuit outputs a level shifted PWM signal which is synchronized to the PWM frequency of the input signal to effectively remove ripple fluctuation in the output signal, circuitry for converting said pulse width modulated signal at said first potential into a pair of current pulse trains triggered by rising edges and falling edges, respectively, of said PWM signal prior to level shifting from said first potential to said second potential; and circuitry for converting said level shifted pulse train signals into a pulse width modulated signal at said second potential, wherein said circuitry for converting the input signal at said first potential to a pulse width modulated signal comprises an AID converter using pulse width modulated encoding comprising a waveform generator for generating a triangular or sawtooth signal synchronized to the PWM frequency of the input signal, a sample and hold circuit synchronized to the PWM frequency of the input signal, and a comparator for determining whether said input signal is greater than or less than said triangular or sawtooth signal.