A 400 W Near-Threshold Feedback Class-C VCO with Auto Amplitude Control.

A 400W near-threshold supply class-C voltage controlled oscillator (VCO) with amplitude feedback loop and auto amplitude control (AAC) is proposed in this paper. The amplitude feedback loop and AAC ensure the robust startup of the proposed VCO and automatically adapts it to the class-C mode in steady state. Consequently, ultra-low power can be achieved in AAC mode and low phase noise, high swing can be achieved in AAC off mode. The proposed VCO with AAC gets ultra-low power consumption by limiting the oscillating amplitude and driving the proposed VCO into the deep Class-C mode. Additionally, the peak value detector is employed in this work to boost the controlling voltage of capacitors bank. Thus, a low on resistance of switch transistors is obtained, which increases the Q value of capacitors bank. The simulated phase noise is 124.5dBc/Hz at 1MHz offset with the 1.16GHz oscillation frequency. In this case, the figure-of-merit including tuning range (FOMT) of proposed VCO is 195dBc/Hz. The proposed VCO is fabricated in SMIC 40nm CMOS process and consumes 0.62mA from 0.65V supply. The measured phase noise is 109dBc/Hz and FOMT is 179dBc/Hz. [ABSTRACT FROM AUTHOR]