Patent ID: 6683489
Filing Date: 2004-01-27
Classification: G05F

Abstract:
A biasing circuit for producing a bias current which is supply-independent and temperature stable, comprising:a first voltage generating circuit which produces a first voltage V1 at an output, the first voltage generating circuit further including a first transistor having a first temperature coefficient and a first aspect ratio; a second voltage generating circuit which produces a second voltage V2 at an output, the second voltage V2 being different from the first voltage V1, the second voltage generating circuit further including a second transistor having a second temperature coefficient that is substantially the same as the first temperature coefficient and a second aspect ratio that is different from the first aspect ratio; a differential amplifier circuit having a first input coupled to the first voltage generating circuit, a second input coupled to the second voltage generating circuit, and an output; a first resistor having a first end connected to the first input, and a second end; a second resistor having a first end connected to the second end of the first resistor, and a second end; a reference resistor having a first end connected to the second end of the second resistor for receiving a reference voltage VREF and for converting the reference voltage to the bias current; and a current mirror circuit coupled to the first end of the reference resistor, the output of the differential amplifier, and to inputs of the first and the second voltage generating circuits.