Low phase noise MMIC VCOs for Ka-band applications with improved GaInP/GaAs-HBT technology

We report on the technology and performance of fully monolithic coplanar voltage-controlled oscillators (VCOs) with GaInP/GaAs-HBTs as the active devices. With our optimized HBT process, the parasitic base resistance R/sub B/ and extrinsic base-collector capacitance C/sub EX/ are significantly reduced. In this way, the maximum frequency of oscillation F/sub max/ is increased from 100 to 170 GHz. This allows us to realize fundamental 38 GHz-VCOs with very low phase noise. At an oscillation frequency F/sub res/=34.2/spl plusmn/0.2 GHz, the VCO reaches phase noise levels of -87 dBc/Hz @ 100 kHz and -108 dBc/Hz @ 1 MHz offset frequency, respectively. To our knowledge, these phase noise values are the lowest GaAs data for Ka-band applications reported so far.