Patent ID: 6882191

Claim:
A frequency doubler device comprising: a first rectifier doubler stage adapted to receive a first input signal having a first frequency and adapted to output a first rectified signal having multiple harmonics; a second rectifier doubler stage adapted to receive a second input signal having the first frequency and offset in phase from the first input signal and adapted to output a second rectified signal, wherein the second rectified signal has the multiple harmonics and is offset in phase from the first rectified signal, wherein the second input signal is offset in phase by approximately 90 degrees from the first input signal; and a differential amplifier stage coupled to the first rectifier doubler stage and the second rectifier double stage and adapted to sum the first rectified signal and the second rectified signal to produce an output signal, wherein the output signal includes a desired output harmonic having a frequency that is double the first frequency, wherein the summing results in a substantial cancellation of unwanted output harmonics in the output signal.