Variable Transconductance Devices

Abstract

The basic monolithic integrated circuit operational amplifier is no doubt the most universally applicable linear i.c. but there are now quite a wide range of other linear integrated circuits available. A general appreciation of the internal circuit operating principles of these devices enables them to be used with greater confidence and leads to an understanding of the function of any external components that are required for their correct operation. Several linear i.c.’s make use of a variable transconductance circuit technique, and this chapter is devoted to a brief theoretical treatment of the variable transconductance principle and discusses the internal circuitry of some devices which use the technique¹. The technique is basically employed to achieve a variable gain, the variable gain facility is developed to provide a device which can perform a four quadrant linear multiplication.