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

A frequency converter comprises a mixer and a variable load arranged to act on at least one of an input and an output of the mixer, and a detector arranged to detect a direct current component of an output signal of the converter. A plurality of states of the variable load are sequentially set and a variation between the direct current components for each one of the plurality of states of the variable load is observed, and at least one parameter influencing the direct current component of the output signal of the frequency converter is adjusted such that the observed variation is reduced. The technique reduces a direct current component at the output of frequency converter arising from leakage of the local oscillator signal and self mixing.