Gm-boosted common-gate LNA and differential colpitts VCO/QVCO in 0.18-μm CMOS
Xiaoyong Li; Shekhar, S.; Allstot, D.J.
Solid-State Circuits, IEEE Journal of
Volume 40, Issue 12, Dec. 2005 Page(s): 2609 - 2619
Digital Object Identifier 10.1109/JSSC.2005.857426
Summary:The demand for radio frequency (RF) integrated circuits with reduced power consumption is growing owing to the trend toward system-on-a-chip (SoC) implementations in deep-sub-micron CMOS technologies. The concomitant need for high performance imposes additional challenges for circuit designers. In this paper, a gm-boosted common-gate low-noise amplifier (CGLNA), differential Colpitts voltage-controlled oscillators (VCO), and a quadrature Colpitts voltage-controlled oscillator (QVCO) are presented as alternatives to the conventional common-source LNA and cross-coupled VCO/QVCO topologies. Specifically, a gm-boosted common-gate LNA loosens the link between noise factor (i.e., noise match) and input matching (i.e., power match ); consequently, both noise factor and bias current are simultaneously reduced. A transformer-coupled CGLNA is described. Suggested by the functional and topological similarities between amplifiers and oscillators, differential Colpitts VCO and QVCO circuits are presented that relax the start-up requirements and improve both close-in and far-out phase noise compared to conventional Colpitts configurations. Experimental results from a 0.18-μm CMOS process validate the gm-boosting design principle.
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