Effects of Local Oscillator Waveform on Mixer Spurious Response Levels

The purpose of this paper is to point out some of the properties of mixer operating in the switching mode and to discuss some of the effects that changes in the waveform of the local oscillator signal have on mixer responses. The operation of most mixers at high local oscillator drive levels can be described in terms of a switching function which includes the width modulation effects caused by the small input signal, it is possible to calculate the levels of the various mixer responses for a variety of local oscillator waveforms. Because it isolates the switching function from the width modulating effects of the input signal, a square wave local oscillator signal is effective in reducing the levels of responses associated with harmonics of the input signal.