Patent ID: 6172564
Filing Date: 2001-01-09
Classification: H03F

Abstract:
An intermodulation (IM) product cancellation circuit for reducing one or more IM products in a carrier signal, the IM product cancellation circuit comprising:a variable oscillator for producing an IM product cancellation signal;a variable phase shifter means for shifting said IM product cancellation signal 180.degree. with respect to an IM product in a carrier signal for canceling an unwanted IM product in the carrier signal;a processor including a memory for storing a look-up table including the identity of the frequency or frequencies of intended signal components of a carrier input signal, said processor connected to said variable oscillator and said variable phase shifter for controlling said variable oscillator and said variable phase shifter means for initiating and maintaining said IM product cancellation signal at substantially the same frequency as the IM product but shifted 180.degree. with respect to the IM product for substantially reducing an unwanted IM product in the carrier signal; anda coupler means for combining the carrier signal with said IM product cancellation signal to produce an output signal the IM product being substantially reduced.