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Precision Differential Transconductance Amplifier

IP.com Disclosure Number: IPCOM000040483D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02

Publishing Venue

IBM

Related People

Authors:
Richetta, RA Schmerbeck, TJ Strom, JD [+details]

Abstract

The amplifier linearly transforms a differential analog voltage signal to a single ended (undifferential) current that is thus proportional to the input voltage. The scale factor is determined by the one resistor R1 shown in the figure. The figure shows a schematic of the basic differential transconductance amplifier. The differential input voltage appears between connectors EIN+ and EIN-. The circuit is designed to drop this entire differential voltage across R1. The current produced across R1 is also generated at output connectors IOUT1 and IOUT2 which thus is proportional to the input voltage between EIN+ and EIN-. So the voltage-to- current conversion impedance is just R1. Multiple copies of the converted current can be produced by adding additional current sources such as Q3,R4 at node 17.