Patent ID: 8471633
Filing Date: 2013-06-25
Classification: G09G,H03F

Abstract:
1. A differential amplifier for outputting a voltage having a signal level which is between a first input voltage and a second input voltage, the differential amplifier comprising: a first differential pair including transistors of a first conductivity type and outputting a first pair of differential currents to a first current node pair based on a difference between a first one of the first and second input voltages and the output voltage; a second differential pair including transistors of the first conductivity type and outputting a second pair of differential currents to the first current node pair based on a difference between a second one of the first and second input voltages and the output voltage; a third differential pair including transistors of a second conductivity type and outputting a third pair of differential currents to a second current node pair based on a difference between the first one of the first and second input voltages and the output voltage; a fourth differential pair including transistors of the second conductivity type and outputting a fourth pair of differential currents to the second current node pair based on a difference between the second one of the first and second input voltages and the output voltage; a first current source provided between a first power supply for providing a first supply voltage and the first differential pair and providing an operating current to the first differential pair; a second current source provided between the first power supply and the second differential pair and providing an operating current to the second differential pair; a third current source provided between a second power supply for providing a second supply voltage and the third differential pair and providing an operating current to the third differential pair; a fourth current source provided between the second power supply and the fourth differential pair and providing an operating current to the fourth differential pair; a first control circuit which controls, in a first operating range, a changing point at which the operating current provided to the first differential pair changes, the first operating range being where amounts of currents flowing, based on the first and second input voltages and the output voltage, through the first and second differential pairs, respectively, become smaller than current amounts set by the first and second current sources, respectively; a second control circuit which controls, in a second operating range, a changing point at which the operating current provided to one of the third and fourth differential pairs changes, the second operating range being where amounts of currents flowing, based on the first and second input voltages and the output voltage, through the third and fourth differential pairs, respectively, become smaller than current amounts set by the third and fourth current sources, respectively; and an output amplification section which generates the output voltage based on a differential current output generated by combining the first and second pairs of differential currents outputted from the first current node pair and a differential current output generated by combining the third and fourth pairs of differential currents outputted from the second current node pair.