Integrated adaptive LO leakage cancellation for W-CDMA direct upconversion transmitters

A method for on-chip implementation is presented to compensate both local oscillator leakage due to finite LO to RF port isolation and input DC offset. It uses an RF power detector and a digital control loop and is intended for use in direct upconversion transmitters. The entire control loop was integrated in a CMOS UNITS transceiver chip. This paper presents the cancellation principle, simulations, and measurement results.