Patent ID: 6822505
Filing Date: 2004-11-23
Classification: H03F

Abstract:
A transconductance-setting circuit, comprising:a first transconductor coupled to a reference voltage source, said voltage source having a positive terminal and a negative terminal, said first transconductor adapted to produce a current output; a reference current sink coupled to said first transconductor, a feedback loop coupled to said first transconductor and said reference current source, said feedback loop adapted to reduce error in said current output and set the transconductance of said first transconductor to a value proportional to the ratio of said reference current and said reference voltage; said first transconductor comprising a first differential transistor pair including: a first transistor having a gate, source and a drain; a second transistor having a gate, source and a drain, said gate of said second transistor coupled to one of said positive or negative terminals of said voltage source and said gate of said first transistor coupled to the other of said positive or negative terminals of said voltage source; and a third transistor coupled to said first and second transistor sources; said circuit further comprising: a fourth transistor coupled to said first transistor and a voltage supply; and a fifth transistor coupled to said fourth transistor, said second transistor and said voltage supply; wherein said feedback loop comprises: a sixth transistor coupled to said fifth transistor and said current reference source; a seventh transistor coupled to said sixth transistor and a common mode voltage source; and an eighth transistor coupled to said seventh transistor and said third transistor.