Calibration of a frequency converter, based on non-dc measurements, to reduce an output dc component arising from local oscillator leakage and self-mixing

摘要

A frequency converter comprises a mixer and a local oscillator (LO) arranged to generate an amplitude-modulated LO signal for the mixer. The converter also comprises a detector arranged to detect a non-direct current component of an output signal of the mixer arising from the amplitude-modulated LO signal. A magnitude of the local oscillator leakage is observed on the basis of the detected non-direct current component of the output signal of the converter, and at least one parameter influencing the non-dc component of the output signal is adjusted such that the observed magnitude of local oscillator leakage is reduced. The technique acts to reduce a direct current component at the output of frequency converter arising from leakage of the local oscillator signal and self mixing.