In an embodiment, an apparatus comprises an in-phase-quadrature (IQ) signal amplifier having an IQ baseband input, an IQ mixer input connected to the IQ signal amplifier, a carrier leakage detector connected to outputs of the IQ mixer, and a carrier-null offset signal generator connected to the carrier leakage detector. The IQ mixer is configured to be driven by an IQ carrier signal. The carrier leakage detector is configured to output an in-phase leakage level measurement and a quadrature leakage level measurement in the absence of an IQ baseband signal at the IQ baseband input. The carrier-null offset signal generator is configured to (i) inject an in-phase carrier-null offset signal based on the in-phase leakage level measurement and (ii) inject a quadrature carrier-null offset signal based on the quadrature leakage level measurement.