Patent ID: 7161392

Claim:
A circuit comprising: a first capacitor a first comparator having an output coupled to the first capacitor a non-inverting input for receiving a high frequency AC waveform an inverting input a second capacitor a second comparator having an output coupled to the second capacitor a first input a second input a first buffer amplifier having an input coupled to the first capacitor an output coupled to the inverting input of the first comparator a second buffer amplifier having an input coupled to the second capacitor an output an inverting amplifier having an input coupled to the output of the second buffer amplifier an output coupled to the first input of the second comparator an operational amplifier having a non-inverting input coupled to the inverting input of the first comparator and the output of the first buffer amplifier an inverting input coupled to the first input of the second comparator and the output of the inverting amplifier.