alignment methods and apparatus for i / q phase and amplitude error correction and image rejection improvement that may be used at the time of circuit fabrication or on chip for use during operation . the alignment method may be used to improve the i / q phase and amplitude accuracy of a direct conversion transceiver or to improve image rejection in an up or downconversion mixer . for alignment purposes , a pilot tone of a selected frequency is used to provide a calibration reference , with adjustments being made in phase and amplitude to drive the i and q phase and amplitude mismatch toward a minimum .