Design of RF Oscillators for Wireless Digital Transmitters

Abstract

Cost reduction is one of the main driving forces for integration. As such, advanced CMOS technologies offer excellent digital functionality and high-density integration capabilities. Properties that persuade designers to exploit new digitally assisted approaches rather than following conventional analogue techniques. Using these new concepts, fully integrated transmitters that operate from baseband up to the pre-power amplifier (PA) stage entirely in the digital domain have become feasible. However, this imposes many coupling issues for different parts of the transceiver, such as the local oscillator. One of the primary building blocks of the transmitter is an oscillator and each modern digital transmitter has to have at least one oscillator, which normally has tough specifications imposed by the standard and transceiver architecture. This thesis focuses on the design of digitally controlled oscillators which could have excellent phase noise, very fine frequency resolution, small footprint and wide tuning range. Moreover, a simple yet an efficient architectural solution for the problem of local oscillator pulling, which will likely be the main cause degrading spectral purity of the TX output in multi radio SoCs has been proposed.