Nonlinear Companding Circuits With Thermal Compensation to Enhance Input Dynamic Range in Analog Optical Fiber Links

Abstract

Measuring systems based on a pair of optical fiber transmitter-receivers are used in medium-voltage testing laboratories wherein the environment of high electromagnetic interference (EMI) is a limitation for using conventional cabling. Nonlinear compensation techniques have been used to limit the voltage range at the input of optical fiber links. However, nonlinear compensation introduces gain and linearity errors caused by thermal drift. This paper presents a method of thermal compensation for the nonlinear circuit used to improve transient signal handling capabilities in measuring system while maintaining low errors in gain and linearity caused by thermal drift.