Patent ID: 6466080
Filing Date: 2002-10-15
Classification: G05F

Abstract:
A constant-current driver circuit comprising:a reference current circuit including a first MOS transistor and a first constant-current source connected to the first MOS transistor and providing a reference current to the first MOS transistor, wherein the reference current circuit generates a gate voltage of the first MOS transistor in accordance with a first control signal; an output current circuit including a second MOS transistor generating an output current having a predetermined ratio to the reference current, a gate of the second MOS transistor being connected to a gate of the first MOS transistor, and a first switch circuit connected to the second MOS transistor in series to on-off control the output current in accordance with a second control signal; a bias circuit connected to a gate of the second MOS transistor to provide a bias voltage to the gate of the second MOS transistor in accordance with a third control signal, wherein variation in the gate voltage of the second MOS transistor in the on control of the output current is suppressed; and a control circuit connected to the reference current circuit, the output current circuit and the bias circuit, receiving an input signal and generating the first to third control signals, wherein the reference current circuit and the output current circuit are operated in the same phase, and the bias circuit is operated in the opposite phase to the reference current circuit and the output current circuit.