Mm-Wave tunable colpitts oscillators based on FinFETs

Abstract

The characteristics of compact tunable Colpitts oscillators built using FinFET transistor technology are presented. As compared to a conventional single gate MOSFET, the use of common-mode FinFET architecture allows for a more relaxed oscillatory criterion for Colpitts oscillator design, while adaption of independent-mode FinFETs bestows a Colpitts oscillator with a simple and efficient means for tunable performance. The frequency can be tuned to an extent of ∼5% of center frequency without the need of any extra components such as varactors. The effect of supply voltage and FinFET dimensions on the oscillation frequency has also been investigated. The oscillation criterion is relaxed when compared to that of an identical design in single gate MOSFET due to the increase of gm by a factor of 2 in case of a common-mode FinFET. No separate capacitors are used between the gate and source as part of a conventional Colpitts oscillator: The higher gate-source capacitance of the FinFET is conveniently utilized to substitute the external capacitor thus reducing parasitics and achieving the mm-wave frequency of 65 GHz and 165 GHz. The phase noise of the oscillator is −95 dBc/Hz at 1 MHz offset, for the case of 65 GHz circuit, which deteriorates in higher frequency versions. The compact and tunable characteristics of the proposed oscillator, along with its high frequency potential, make it suitable for applications such as on-chip wireless interconnects required for kilo-core computing that have hard limits on area and power but requires very precise tuning of the carrier.