Patent ID: 6515546
Filing Date: 2003-02-04
Classification: G05F,H03F

Abstract:
A circuit for biasing a first transistor having a control terminal, current-sink terminal, and current-source terminal and capable of operating from a power supply having positive and ground terminals, the circuit comprising:a. a second transistor having a control terminal, current-sink terminal and current-source terminal, i. wherein the control terminal of said second transistor is connected to the control terminal of such first transistor in a current-mirror configuration, and ii. wherein the current-sink terminal of said second transistor is connected to the ground terminal of such power supply; b. a first resistor connected between the current-source terminal of said second transistor and the positive terminal of such power supply; c. a feedback circuit, including i. a non-inverting amplifier having input and output ports, (1) wherein the input port of said non-inverting amplifier is connected to the node formed by said first resistor and the current-source terminal of said second transistor; and ii. a feedback transistor having a control terminal, current-sink terminal, and current-source terminal, (1) wherein the control terminal of said feedback transistor is connected to the output port of said non-inverting amplifier, (2) wherein the current-sink terminal of said feedback transistor is connected to the node formed by the connection of said second transistor to such first transistor, and (3) wherein the current-source terminal of said feedback transistor is connected to the positive terminal of such power supply, whereby said non-inverting amplifier increases the gain of the feedback circuit so that the bias circuit is relatively insensitive to fluctuations in supply voltage or temperature.