Abstract
A K-band low-voltage voltage controlled oscillator (VCO) implemented in standard 65-nm bulk CMOS process is proposed. By using the proposed gate AC-coupling technique and biasing the cross-coupled transistors in moderate inversion region, the oscillator core operates under ultra low supply voltage with acceptable current efficiency. Reverse short-channel effect is also employed to reduce the threshold voltage of the cross-coupled transistors. Operating from 23.1 to 24.8 GHz, the fabricated VCO is able to work under supply voltage as low as 0.25 V with a core power consumption of 1 mW.