Design and test of a 73 GHz push-push oscillator using voltage controlled tuning without varactors

Two push-push mmWave voltage controlled oscillators (VCOs) implemented in a commercial GaAs pHEMT process are presented, operating at 73 GHz. Frequency tuning uses Vgs bias control, with no additional varactors. In a set of dies, the maximum tuning range achieved is 795 MHz for design MMIC V4 and 274 MHz for design MMIC V6. A 1 dB RF output power variation is seen over the Vgs tuning range for device MMIC V6. A phase noise of -111.8dBc/Hz @ 6 MHz offset is seen for the best performing configuration, and an output power of circa -5 dBm is provided by the measured devices. An initial analysis technique is presented to help predict the tuning range for an architecture at the outset of a design.