Voltage-controlled isolated linear resistors with wide operation range

Abstract

In this paper, cadmium sulfur (CdS) type photo-couplers are employed to achieve the voltage-controlled isolated resistors (VCIRs). The feedback technique is applied to overcome the inherent non-linear characteristics of photo-couplers using current conveyors, and thus a good transient response of VCIRs can be obtained. They can be employed to achieve noise suppression and high voltage isolation since the circuit has no common ground between the input and output terminals. Their resistances are proportional to the controlled voltage and range from 400 to 400 k. The mathematical model is also proposed. Experimental responses and simulation results demonstrate the dynamic and static characteristics of VCIRs.