Single - Amplifier Biquadratic MOSFET – CFilters

This dissertation discusses the theory of single-amplifier biquadratic filters (SABs) and their implementation as CMOS video-frequency filters. It shows that building filters as cascades of single-amplifier biquadratic MOSFET–C sections is a viable alternative to using biquadratic Gm–C filter sections. The advantage of MOSFET–C SABs is that they typically use less chip area than a Gm–C filter with equivalent speed, distortion, noise, and power consumption. The first part of this dissertation discusses the theory of integrated amplifiers, provides a new perspective of the currentmode vs. voltage-mode debate, and discusses the theory of SABs and the effects that amplifier non-idealities have on them. The second part discusses second-order MOSFET–C networks and how to design filters with them, presents perfectly symmetrical video-frequency current amplifiers, one with fixed gain and one with variable gain, and contains measurement results of test circuits from two chips. The third part presents a brief comparison of the MOSFET–C SABs presented in this dissertation to other video-frequency filters, and finishes with a discussion of design trade-offs and ideas for future research on the topic.