1.1 to 1.9GHz CMOS VCO for tuner application with resistively tuned variable inductor

A VCO is fabricated in 0.35 mum CMOS technology for tuner application as a proof of concept for a novel method of resistively tuning the inductance of an LC VCO. By employing a transformer as inductor, L is varied by changing the secondary coil current using active resistors. This eliminates the need for using multiple inductors to cover the frequency spectrum of 1.1 to 1.9 GHz, resulting in large savings in area. Power consumption is comparable to other known transformer based, magnetic tuning inductance methods due to its single powered VCO core implementation. It draws about 6.8 mA from a 3 V supply. The achievable tuning range of 1.06 to 1.88 GHz (56%) and phase noise of -116.1 dBc/Hz is adequate for tuner application.