Patent ID: 8653893
Filing Date: 2014-02-18
Classification: G09G

Abstract:
1. An output circuit comprising: a differential input stage; an output amplifier stage; a current control circuit; an input terminal; an output terminal; and first to fourth power supply terminals, wherein said differential input stage includes a first differential pair that includes a pair of transistors which have a pair of inputs for differentially receiving an input voltage at said input terminal and an output voltage at said output terminal, respectively; a first current source that drives said first differential pair; a first current mirror that includes a pair of transistors of a first conductivity type connected between said first power supply terminal and first and second nodes and receiving a pair of output currents of said first differential pair; a second current mirror that includes a pair of transistors of a second conductivity type connected between said second power supply terminal and third and fourth nodes; a first floating current source circuit that is connected between said second node, to which an input of said first current mirror is connected, and said fourth node, to which an input of said second current mirror is connected; and a second floating current source circuit that is connected between said first node, to which an output of said first current mirror is connected, and said third node, to which an output of said second current mirror is connected, wherein said output amplifier stage includes: a first transistor of a first conductivity type that is connected between said third power supply terminal and said output terminal, and that has a control terminal connected to said first node; and a second transistor of a second conductivity type that is connected between said fourth power supply terminal and said output terminal, and that has a control terminal connected to said third node, and wherein said current control circuit includes at least one of a first circuit and a second circuit, said first circuit that including a second current source connected to said first power supply terminal, said first circuit performing control of switching between activating said second current source to couple a current from said second current source to one of a current input to said first floating current source circuit and a current output from said first floating current source circuit, and deactivating said second current source, depending on whether or not a voltage difference between said output voltage at said output terminal and a voltage at said first power supply terminal is greater on comparison by more than a predetermined first preset value than a voltage difference between said input voltage at said input terminal and said voltage at said first power supply terminal, said second circuit that including a third current source connected to said second power supply terminal, said second circuit performing control of switching between activating said third current source to couple a current from said third current source to the other of a current input to said first floating current source circuit or to a current output from said first floating current source circuit, and deactivating said third current source, depending on whether or not a voltage difference between said output voltage of said output terminal and a voltage at said second power supply terminal is greater on comparison by more than a predetermined second preset value than a voltage difference between said input voltage at said input terminal and a voltage at said second power supply terminal.