| The growing demand for higher data transfer rates and lower power consumption has had a major impact on the design of RF communication systems. In both wireless and wireline applications, this has been achieved using more spectrally efficient modulations and/or wider channel bandwidth in combination with engineering techniques to lower power and fabrication costs. Furthermore, as communication standards evolve and new applications are created, systems not only have to cope with a more crowded spectrum, they must also support a larger number of legacy standards for reasons of backward compatibility. This has resulted in a trend promoting more wideband and spectrally adaptive devices.; One of the most critical components in modern communication devices is the VCO. Being at the heart of the frequency synthesizer, the VCO performs indispensable functions in the transmission and reception of data. For systems with high dynamic range requirements, the VCO must achieve a correspondingly high degree of spectral purity so as not to degrade the SNR (or sensitivity) excessively. This can be particularly challenging for wideband systems because conventional wideband VCOs have poor phase noise performance. To this date, the only effective solution to this challenge has been to use multiple low-noise narrowband VCOs, each covering a portion of the required range. While conceptually simple, this solution is far from ideal due to its high cost and increased design complexity.; In light of the above observations, the main goal of this thesis is to identify successful measures for wideband low-noise frequency synthesis. Using an LC VCO as its main vehicle, characteristics of wideband low-noise frequency synthesis are analyzed, leading to proposed techniques. A prototype is implemented to validate our analysis and demonstrate the feasibility of wideband low-noise LC VCOs. |
