A Ku-band low-phase-noise transformer coupled VCO for satellite communications

A Ku-band voltage-controlled oscillator (VCO) with a low phase noise is presented in this paper. By increasing the third-harmonic of the fundamental frequency, the transformer-based topology can enforce a pseudo-square voltage waveform in the LC tank to reduce the phase noise. Implemented in a 90-nm standard CMOS technology, the VCO exhibits an average phase noise of -117.2 dc/Hz at 1 MHz offset over a 9.5-11.7 GHz tuning range. The oscillator only occupies 0.2 mm
²
while drawing 13.3 mA from the 1.2-V power supply, and the achieved FoM is 185.4 dBc/Hz. The proposed VCO is suitable for applications of satellite communications.