Patent ID: 6541945
Filing Date: 2003-04-01
Classification: H03F

Abstract:
An apparatus for regulating a source potential that is provided to a source node by a source circuit, the apparatus comprising:a first amplifier circuit that includes a first input that is coupled to the source node, a second input that is coupled to a first reference potential, and an output that is arranged to provide a first control signal; a second amplifier circuit that includes a first input that is coupled to the source node, a second input that is coupled to a second reference potential, and an output that is arranged to provide a second control signal; a first bias stage that is arranged to provide a first bias signal in response to the first control signal; a second bias stage that is arranged to provide a second bias signal in response to the second control signal, wherein the first and second bias stages are arranged to cooperate with one another such that one of the first and second bias signals will provide a dominant bias signal; and a shunt circuit that is coupled to the source node and arranged to shunt the source potential in response to the dominant bias signal such that closed loop regulation is maintained when one of two regulation loops are defective, wherein the first regulation loop includes the first amplifier circuit, the first bias stage, and the shunt circuit, and the second regulation loop includes the second amplifier circuit, the second bias stage, and the shunt circuit.