Synthesis of current-mode circuits based on nullor relocation

number: 
992
English
Degree: 
Author: 
Naseem Kadhim Al-Mudhaffar
Supervisor: 
Dr. Fawzi M. Al-Naima
year: 
1996
Abstract:

This thesis presents an algorithm for generating equivalent active circuits using second generation current conveyors as active building blocks instead of the OP/AMPs This algorithm uses nullor relocation based on minimum number of current conveyors assuming that the current conveyors and op-amps are ideal. The procedure for this algorithm is divided into three main steps: forming an RC nullor network from an RC OP-AMP network, generating equivalent RC nullor networks and implementing RC current conveyor networks using the theory of matching in bipartite graphs. Examples are considered to demonstrate the algorithm steps. A program generating equivalent current mode circuits from a given op-amp circuit is discussed. The program consists of three main parts controlled and run by the main program. Each part is discussed and illustrated with the aid of flow charts. A formatting of the input file that includes a description of the network to be analyzed is presented with the node connections of the generated circuits. Only the results for circuits having up to four op-amps are considered, where it is shown that the number of current-mode circuits may approach thousands. The equivalent circuits being in voltage-mode or current-mode exhibit identical performance for ideal active elements. However, when non-ideal op-amps and current conveyors are considered, differences will be observed in the performance of various circuits. Comparable models of op-amps and current conveyors are used to ensure compatibility of the comparison results. It is shown that some of the current-mode circuits generated by the program enable superior performance to be achieved, even in cases where high performance op-amps have been used in the original circuit.