US Patent 7412006 Method and apparatus for RF carrier feedthrough suppression

A method includes performing a search method to determine a pair of receiver path correction signals, performing the search method to determine a pair of transmitter path correction signals, and using the pairs of receiver path and transmitter path correction signals to suppress a carrier signal. An apparatus includes a first pair of summers, an upconverter circuit coupled to the first pair of summers, a multiplexer coupled to the upconverter circuit, to a ground, and to an RF front end, a downconverter circuit coupled to the multiplexer, a second pair of summers coupled to the downconverter circuit, and a correction circuit coupled to the first and second pairs of summers.