A Continuous-Time Modelling and Design Approach for Oversampled Passive Switched-Capacitor Filters

Integrated technology advances towards shorter length transistors with faster operation frequencies and lower supply and threshold voltages. While these trends are pushed by digital performance, analog and RF designs do not necessarily benefit from them. Traditional high gain and high bandwidth operational amplifiers become harder to design, and thus topologies based on "digital friendly" components such as switches and capacitors can become preferable. In terms of filter design, these trends favour passive switched-capacitor networks, where active components (such as operational amplifiers) are not needed to transfer charge in between capacitors. This thesis proposes a simplified continuous-time approach for modelling, design, analysis, and simulation of oversampled switched-capacitor circuits focusing on the passive switched-capacitor filters. The model provides an intuitive understanding of these structures by letting designers reach transfer functions and noise characteristics with good accuracy and without the need to go through complicated charge-balance equations. The aim of the model is mainly to give designers a tool that can lead to innovations through intuitive understanding. It is applicable to a variety of topologies including multi-phase passive switched-capacitor filters, switched-capacitor integrators, as well as switched-capacitor DC/DC converters. With the proposed model, for the first time, complex-conjugate poles are integrated on silicon by using only switches and capacitors. A continuous-time approach is reported to implement low-pass transfer functions with a sharper frequency profile compared to the passive switched-capacitor topologies present in the literature. Theory and simulation results are verified with measurements performed on the filter prototype integrated in a 0.13 um CMOS technology. The prototype has a cut-off frequency of 470 kHz, 150 uW power consumption from a 1.2 V power supply, 92 dB SFDR, and an active area of 0.06 mm2.Ph.D