Simple high speed precision transconductance amplifier circuits

摘要

A simple high speed precision transconductance amplifier circuit having a low offset. The circuit uses as an input stage two substantially identical transistors of a first conductivity type connected in series so as to have the same current there through, neglecting base currents. A second stage uses two substantially identical transistors of a second conductivity type connected in series, with the output of the amplifier being a current mirrored from the second stage. The offset is maintained low by maintaining the VBE of the transistors in the two stages substantially identical by connecting together the base and collector of one of the transistors in one stage and coupling the resulting VBE of the transistor so coupled to one of the transistors of opposite conductivity type in the other stage. Various embodiments and variations are disclosed.