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

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 6dB. The proposed circuit was designed and simulated by ADS simulator using 0.18m TSMC RF CMOS design kit. The phase noise's at 3MHz frequency offset and carrier frequencies of 2.43GHz and 2.6GHz are -141dBc/Hz and -135dBc/Hz, respectively, while the total power consumption is 14mW under 1.8V supply voltage. Tuning range is from 2.43GHz to 2.6GHz. The figure of merit (FOM) values for the proposed LC-QVCO at 3MHz frequency offset are -187.6dBc/Hz and -182.3dBc/Hz for 2.43GHz and 2.6GHz carrier frequencies, respectively. [ABSTRACT FROM AUTHOR]