Synthesis of Multiple-Loop Feedback Switched-Capacitor Structures (Active Filters)

123 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.In this dissertation a new switched-capacitor (SC) design technique is presented. The design method is based on a building block approach where the desired transfer function is realized in a multiple-loop feedback (MF) topology by interconnecting parasitic-insensitive SC circuits. The SC structures obtained in this manner share the advantages of the cascade approach in the sense that they are modular and are able to realize a great variety of general filtering and/or equalization functions. Furthermore, the flexibility associated with the feedback paths in MF topologies provides the means for obtaining improved sensitivity performance as compared to the performance of cascade structures.Two types of SC building blocks, either first or second-order, are considered for implementation in MF topologies. The use of second-order blocks, that is, SC biquads, proves to be more advantageous, resulting in significant reduction in the design complexity, meanwhile providing the necessary degrees of freedom which are used for sensitivity improvement via computer-aided optimization.A computer program is developed for the design and optimization of multiple-loop feedback SC structures. An extended version of an SC simulation program is also developed so that a Monte Carlo-based sensitivity analysis could be performed on the resulting SC structures. Several design examples are carried out. The optimized MF structures are found to have passband sensitivity performances comparable to that of the low-sensitivity LC ladder-based SC structures, when realizing equiripple filters. Furthermore, when both filtering and equalization are to be performed, that is, for cases where the passband is no longer flat or equiripple, the MF structures are found to have superior passband performance compared to the cascade structures.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD