Monolithic Ka-band VCO with wide tuning range

This paper reports on the design procedure and mesurement results of a Ka-band MMIC VCO utilizing a 0.15 um T-gate GaAs P-HEMT technology. A balanced buffer amplifier is also developed for assurance of output power higher than 10 dBm. The VCO with center frequency of 35 GHz exhibits a tuning range of up to 3 GHz and typical output power of 10 dBm at 35 GHz without the amplifier. The best measured phase noise at 1MHz offset is - 106 dBc/Hz. The buffer amplifier exhibits a typical gain of 5.9 dB with 15dBm output power. A lange coupler is used for a good matching between the VCO and amplifier.