A Wideband Quadrature VCO Using a Novel Tail Current-Clipping Technique

Abstract

This thesis presents a Quadrature VCO (QVCO) architecture using a novel tail current-clipping technique that improves the phase noise performance of a traditional QVCO by about 4 dB while obtaining a tuning range of about 4 to 5 GHz. This work introduces an innovative idea based on a new approach of implementing a QVCO without an explicit conventional parallel or series coupling network and eliminates some of the issues associated with a traditional QVCO such as bimodal oscillations and phase noise degradation due to the coupling network.

The proposed structure has a lot of advantages over the traditional P-QVCO in terms of both phase noise and power consumption. The proposed QVCO was fabricated in the 40 nm CMOS technology. The measured phase noise at 4.9 GHz was about -123.2 dBc/Hz at 1 MHz offset frequency while the quadrature error was less than 3° over the complete tuning range. The proposed architecture consumes a power of about 7.5 mW from a supply of 1.1 V with a figure-of-merit (FoM) of 188.27 dBc/Hz at 4.9 GHz output frequency.