Harmonic reject mixer with active phase mismatch compensation in the local oscillator path

摘要

A harmonic rejection mixer having a phase rotator fed by a local oscillator signal. The local oscillator signal has a reference frequency. The phase rotator produces a plurality of output signals, each one of the signals having a common frequency related to the reference frequency and having different relative phase shifts. A plurality of mixer sections, each one of the sections being fed an input signal and a corresponding one of the plurality of output signals mixes the local oscillator signal with the corresponding one of the plurality of output signals fed thereto. A combiner combines the mixer signal from the plurality of mixer sections into a composite output signal. A detector detects energy in a harmonic of the composite signal and for adjusting the output signal of the phase rotator to reduce the selected harmonic of the composite signal.