New fully differential variable gain instrumentation amplifier based on a DDA topology

Abstract

A two-stage Fully differential Differential Difference AmpliJier (FDDA) cell is presented. The input linear transconductance ports and the two stage topology are referred and the open-loop characteristics discussed. Based on this fully differential analogue cell, a new fully differential variable gain instrumentation ampliJier is proposed. This new topology is based on the previous described FDDA cell, with a voltage-controlled differential transconductance cell used on the feedback loop of the ampllJer to control the ampli3er's gain. The gains can be continuously tuned within one decade variation range by a controlling voltage V, This decade range is set by two equal feedback resistors Rg Simulation results are discussed and applications of these analogue building blocks in a modular architecture for smart sensor development are referred