Voltage-mode To Current-mode Circuit Transformation

With the development of modern integration technology, the conventional operational amplifier based analog voltage-mode circuits are not able to meet the increasing requirements of circuit design. Compared to the voltage-mode counterparts, current-mode circuits have such potential advantages as wider bandwidths, higher slew rate, lower power consumption and better performance in high frequency. These advantages are attractive to VLSI implementation of analog signal processing circuits. Analog voltage-mode technologies have been well established for several decades and possess quite matured design theories and rich application experiences. Therefore, it provides an easy and prompt way of current-mode circuits design to utilize the expertise of voltage-mode to current-mode by transforming voltage-mode to current-mode.In this dissertation, four kinds of existing approaches of voltage-mode to current-mode circuit transformation are introduced-adjoint network transformation, nullor concept based transformation, extended dual transformation and equivalent building block transformation. An especially emphasis is placed on the analysis of equivalent building block transformation. Besides the equivalent building blocks presented in theorem, five new building blocks are proposed. An investigation on the influence of CCII's input and output impedance is implemented through simulation and theoretical frequency field analysis and comparison of all the building blocks' performance are made. Based on the equivalent building block theorem a novel method is presented: an Opamp's equivalent CCII block diagram is firstly proposed by applying the principle of Opamp and CCII. This new method is based on the replacement of Opamp with its equivalent CCII block diagram and adjoint network theorem. It permits to generate current-mode CCII based circuits from voltage-mode Opamp based counterparts with voltage signals as well as current signals. The new approach is quite easy to apply and more general applicable than the equivalent building block theorem. Illustrative example and simulation result are given to verify the correctness of the new approach.