A Low Phase Noise LC Quadrature VCO Using Impulse Shaping Based on Gaussian Pulse Generator

摘要

This paper presents a new tail current-shaping technique to improve the phase noise of an LC quadrature VCO (LC-QVCO) based on Gaussian pulse generator (GPG). The GPG makes a narrow pulse from oscillator sinusoidal output and injects it back to gates of tail transistors to reduce the root-mean-square (RMS) value of impulse sensitivity function (ISF) and to improve phase noise. It will be shown that by utilizing a GPG, total phase noise improvement will be as high as 6 dB. The proposed circuit was designed and simulated by ADS simulator using 0.18 mu m TSMC RF CMOS design kit. The phase noise's at 3MHz frequency offset and carrier frequencies of 2.43 GHz and 2.6 GHz are -141 dBc/Hz and -135 dBc/Hz, respectively, while the total power consumption is 14 mW under 1.8 V supply voltage. Tuning range is from 2.43 GHz to 2.6 GHz. The figure of merit (FOM) values for the proposed LC-QVCO at 3MHz frequency or set are -187.6 dBc/Hz and -182.3 dBc/Hz for 2.43 GHz and 2.6 GHz carrier frequencies, respectively.