Telefonaktiebolaget LM Ericsson (publ)
Local oscillator leakage detecting and cancellation

Abstract:

A mixer circuitry comprises a mixer, a local oscillator (LO) leakage detector, a digital LO leakage cancellation controller and a DAC arrangement. The mixer is configured to mix a first LO signal having an LO frequency f.sub.LO with an intermediate frequency (IF) signal and generate an output signal, i.e. a wanted signal. The LO leakage detector measures the LO leakage at the output of the mixer in the presence of the wanted signal. Then in the digital LO leakage cancellation controller, a digital algorithm is run that automatically adjusts the LO leakage in the mixer by steering the digital-to-analog converter arrangement such that the intermediate frequency input signal level to the mixer is adjusted.