Patent ID: 7679432
Filing Date: 2010-03-16
Classification: H03F

Abstract:
1. A circuit for providing dynamic current, suitable for an operation amplifier, the circuit comprising: a first transistor, having a gate, a drain and a source, wherein the gate of the first transistor receives an output signal outputted by an output terminal of the operation amplifier, the source of the first transistor receives a first common-mode level, and the drain of the first transistor receives a first dynamic current; and a second transistor, having a gate, a drain and a source, wherein the gate of the second transistor receives the output signal, the source of the second transistor receives a second common-mode level, and the drain of the second transistor receives a second dynamic current, wherein two input signals are respectively received by a first input terminal and a second input terminal of the operation amplifier, and the input signals and the output signal have the first common-mode level and the second common-mode level respectively, wherein when the input signals respectively received by the first input terminal and the second input terminal get a first transition, the first transistor is turned on and the second transistor is turned off, so that a bias current of the first input terminal of the operation amplifier is increased by the first dynamic current; when the input signals respectively received by the first input terminal and the second input terminal get a second transition, the first transistor is turned off and the second transistor is turned on, so that the bias current of the second input terminal of the operation amplifier is increased by the second dynamic current; and when the input signals respectively received by the first input terminal and the second input terminal are in a steady state, the first transistor and the second transistor are simultaneously turned off, so that the bias currents of the first input terminal and the second input terminal of the operation amplifier are not increased by both of the first dynamic current and the second dynamic current.