A Pulse-Tail-Feedback LC-VCO with 700Hz Flicker Noise Corner and -195dBc FoM

Aravind Tharayil NARAYANAN  Kenichi OKADA  

IEICE TRANSACTIONS on Electronics   Vol.E102-C    No.7    pp.595-606
Publication Date: 2019/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2018ECP5044
Type of Manuscript: PAPER
Category: Electronic Circuits
oscillator,  LC-VCO,  PLL,  flicker noise,  pulse VCO,  phase noise,  tail feedback,  

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This paper proposes a pulse-tail-feedback VCO, in which the tail transistor is driven using pulse-shaped voltage signals with rail-to-rail swing. The proposed pulse-tail-feedback (PTFB) VCO relies on reducing the current conduction period of the tail transistor and operating the tail transistors in triode region for reducing the flicker and thermal noise from the active elements. Mathematical analysis and circuit level simulations of the phase noise mechanism in the proposed PTFB-VCO is also presented in this paper for validating the effectiveness of the proposed technique. A prototype LC-VCO with the proposed PTFB technique is fabricated in a standard 180nm CMOS. Laboratory measurement shows a power consumption of 1.35mW from a 1.2V supply at 4.6GHz. The proposed PTFB-VCO achieves a flicker corner of 700Hz, which enables the VCO to maintain a fairly constant figure-of-merit (FoM) of -195dB within a wide offset frequency range of 1kHz-10MHz.