Impact of the semiconductor diode structure on the virtual local oscillator leakage of GaAs sub-harmonic mixers

Diode mismatch in an anti-parallel diode mixer results in an unwanted virtual leakage at twice the local oscillator pumping frequency. Random variability in a fabrication process is one of the sources of diode mismatch. In some fabrication processes, a diode usually consists of a transistor with source and drain shorted together. The layout of this structure introduces a systematic source of diode mismatch. An informed selection of the fabrication process is crucial in minimizing the systematic source of diode mismatch and improving the virtual local oscillator leakage.