Ultra-wideband millimetre-wave self-oscillating mixer

The performance of an ultra-wideband millimetre-wave GaAs self-oscillating harmonic mixer (SOHM) is presented. Conversion gain, minimum detectable signal (MDS) and `self-pumping¿¿ power level have been measured for the 30 GHz frequency coverage centred at ~ 85 GHz. Sensitivity better than ¿¿71 dBm (without automatic frequency control) using 33 MHz bandwidth, and conversion gain as high as 12 dB have been achieved. For input mm-wave dynamic range of 55 dB (from ¿¿20 dBm to ¿¿75 dBm), a useful down-conversion gain-compression has led to a corresponding variation of only 0.5 mV in the peak-to-peak 70 MHz IF signal (from 0.94 mV to 0.44 mV).