A common‐mode replica compensated inductor–capacitor voltage‐controlled oscillator for mixed‐signal system‐on‐chip applications

Abstract

SUMMARYA novel 1.57GHz complementary metal-oxide semiconductor inductor-capacitor voltage-controlled oscillator with the common-mode replica compensation is introduced for mixed-signal system-on-chip applications. In order to alleviate power line disturbances, the center tap node of differential symmetric inductor and the replica biasing circuit are adopted in the differential voltage regulating unit to reduce power supply sensitivity. In addition, this proposed design also leads to low tuning gain and low power dissipation. The post-layout simulation results under the Taiwan Semiconductor Manufacturing Company's mixedsignal 0.18μm 1P6M process show that the proposed design achieves power supply rejection of À68.6dB at low frequencies and 1.2MHz/V pushing sensitivity. It exhibits phase noise of À130.6dBc/Hz at a 1MHz offset from a 1.57GHz carrier yet dissipates only 5.58mW under a 1.8V power supply.

Survey of integrated‐circuit‐oscillator phase‐noise analysis

“…For ring oscillator supply noise or tail-current noise, this technique works quite well (cf. [72,79]); note that in the context of supply-induced phase noise, one can also combine the parasitic VCO gain with smallsignal gains of supply regulation circuitry (e.g., low-dropout regulators and amplitude-control loops) and perform LTI analysis similar to that in the conversion method [85]-such techniques likewise facilitate PLL phase-noise analysis [191]. However, for LC oscillators, the method is harder to apply unless one can obtain higher-order corrections to f osc (e.g., for varactor-tuned oscillators, see [80,82], and for examples with Colpitts and differential LC oscillators based on the Groszkowski nonlinear frequency shift [160], see [86]).…”

A 4.8–6.8 GHz low phase noise LC VCO in 0.13‐µm CMOS technology

“…Many factors of a LC VCO contribute to the phase noise, such as tail current source, passive devices, and so on. Accordingly, some kinds of techniques have been proposed to optimize these noise sources. Current source switching is adopted to quicken the drain current switching of cross‐coupled transistors, so the current duty cycle is reduced and a lower upconversion of flicker noise from current source is achieved .…”