Transconductance amplifier, e.g. for variable limit frequency filter - has seven current mirrors and two PNP input transistors providing inverting and non=inverting inputs

摘要

The transconductance amplifier with four current mirror stages contains a fifth consisting of pnp transistors with its reference port connected to positive rail, its input to the output of the first current mirror and its output with the inputs of sixth (60) and seventh (70) current mirrors which drive the second and third current mirrors respectively and whose reference ports are connected to input transistor (1,2) emitters. Two pnp input transistors (1,2) have collectors connected to negative rail and bases connected to an inverting (101) or non inverting (102) input. Wilson current mirrors can be used instead of a simple type. USE/ADVANTAGE - E.g. for filters with adjustable limit frequency or variable gain amplifiers. Linear region is extended and common mode input range including negative supply voltage is achieved.