New multiple input fully differential variable gain CMOS instrumentation amplifier

A new fully differential multiple differences instrumentation amplifier (MDIA) with voltage controllable gain is presented. This new instrumentation amplifier (IA) topology is based on a new fully differential multiple differences amplifier cell or FDMDA. Based on this fully differential analogue cell, a new fully differential multiple input instrumentation amplifier with variable gain is proposed. This new IA topology offers three differential inputs with a voltage-controlled differential linear transconductor in the amplifier's feedback loop to control its differential voltage gain. This gain can be continuously tuned within a gain decade range by an analogue controlling voltage V/sub g/. Two equal feedback resistors R/sub g/ set the gain decade variation range, allowing gains between 15 and 60 dB. Simulation results of the developed structure are presented and discussed and some applications of this multiple input amplifier are referred, namely in the processing of several differential voltage analogue sensor signals.