Analysis and Design of mm-Wave Harmonic Oscillators in CMOS Technology

The future of wireless communication systems envisions higher operating frequencies and improved bandwidth efficiency. Millimeter-wave (mm-wave) frequency bands offer large bandwidth and are therefore well-suited to supporting very high data rates. Complex modulation schemes, such as high-order quadrature amplitude modulations (M-QAM), are required to increase the channel efficiency. However, from an analog circuits perspective, this progress poses increasingly demanding challenges in transceiver design. Any wireless communication system requires a highly accurate LO signal, since it serves as the carrier that will be modulated by the baseband signal containing the information. As the carrier frequency and modulation complexity increase, the accuracy of the LO becomes even more critical. This thesis deals with the analysis and design of several realizations of harmonic oscillators, which is the core of the frequency synthesizer and is the bottleneck for the accuracy of the LO signal. The first design proposed is a quadrature voltage-controlled oscillator (QVCO), which is crucial for upconversion and downconversion of the signal in modern wireless transceivers. This thesis presents a novel technique that leverages coupled phase-locked loops (PLLs) to realize QVCO. This solution allows for independent optimization of quadrature accuracy and phase noise, breaking the trade-off between them that is typical of conventional QVCO realizations. Analysis, design and measurements are presented. Digitally controlled harmonic oscillators (DCOs) suitable for integration into digital phase-locked loops (DPLLs) are then introduced. There has been extensive research into DPLLs in recent years, as DPLLs take full advantage of device scaling, whereas the design of their analog counterparts becomes more challenging as the technology scales. Two DCO realizations covering different frequency bands are designed. The proposed prototypes have been taped-out, and measurements results are shown in this thesis.