In this thesis, techniques for reducing the supply voltage and for raising the level of integration of SiGe RFICs are studied. Methods for making circuits more robust through the use of feedback have been implemented in both VCOs and high frequency filters. This research has resulted in an improved understanding of the principles of operation of many of these circuits.

Specifically, this work discusses the design of LNAS, VCOs, filters, and mixers for 5GHz radio applications at 1.8V. A notch filter with automatic Q tuning is integrated with the LNA to provide the opportunity for image rejection. The receiver had a gain of 19.8dB, noise figure of 4.5dB, and an IIP3 of -23dBm. The VCO featured a tuning range of 600MHz and had a free running phase noise of -115.8dBc/Hz at 1MHz offset.

Detailed analysis of the operation of the notch filter was undertaken including a study of the mechanisms determining its linearity, noise performance and stability. As well, a method for automatically Q tuning the filter was analyzed and implemented to demonstrate this concept.

Also VCOs with automatic amplitude control loops were studied as the basis for the Q-tuning loop used in the filter. The detailed operation of these loops is presented along with methods to design the loops for best possible performance. VCOs topologies were also optimized for low voltage operation. The VCO work also led to a study of how phase noise is generated in these circuits, ways to better understand it, and finally how to minimize its effect on the circuit.