Switching Current Technology And Its Applied Research In The Filter Design

In this thesis, theory of switched-current (SI) technology and its application in the design and synthesis of active filters are researched deeply and systematically. Some new switched-current building-blocks and exact approach methods of switched-current filters (SIF) are proposed from modern LC networks and switched capacitor (SC) technology. Based on the analysis of operation principles of switched-current circuits, some true switched-current building-blocks are proposed and reviewed, which include the delay cell, generalised integrator, generalised differentiator, LDI cells, double-sampling bilinear building-blocks, bilinear feed-forward differentiator, third-order building-blocks, integrator and differentiator based biquadratic filter sections and their modified structures. To compensate the error originated from the non-ideal character of the SI circuits, some novel structures based on the technology of negative feedback, fully differential, class AB, SnI and other technologies to compensate the clock feed through effects are proposed and analyzed. The exact design methods of switched-current filters are summarized, such as the director synthesis of Z-plane, Euler mapping, state variable analysis, matrix decomposition, and signal-flow-graph simulation of the LC and switched capacitor prototypes. At the same time, a modified leftdecomposition matrix method is proposed to overcome the usual problems of large silicon area, high sensitivity and component spreads by minimizing the input circuits. Examples of switched-current low-pass, high-pass and band-pass filters are given to verify the feasibility of these methods. To make the exact design of low-sensitivity switched-current high-pass filters be convenient, a new design methods using the novel bilinear feed-forward differentiator is proposed. At the end two examples about digitally programming FIR filter and SI-OTA auto-tuning filter are given.