A MMIC GaN HEMT Voltage-Controlled-Oscillator with high tuning linearity and low phase noise

This paper presents a MMIC GaN HEMT Voltage-Controlled-Oscillator (VCO). The VCO is tunable between 6.45-7.55 GHz with good tuning linearity, average output power about 1 dBm, and a good phase noise with little variation over the tuning range. For a bias of V-d/I-d = 6 V/33 mA, the measured phase noise is -98 dBc/Hz @ 100 kHz and -132 dBc/Hz @ 1 MHz offset frequencies, respectively. To the author's best knowledge, this is the lowest phase noise reported for a VCO in GaN HEMT technology with comparable oscillation frequency and tuning range. The 1 MHz offset phase noise is also comparable to state-of-the-art GaAs-InGaP HBT VCOs with similar tuning range.