Output circuit, data driver, and display device

摘要

An output circuit is capable of supporting a high-speed operation, suppressing power consumption, and controlling its area. The output circuit has a differential input stage, an output amplification stage, and an amplification boost circuit, in which the amplification boost circuit has a differential pair of a second conductivity type and load element pair, and includes a first current source circuit for controlling current supply to an input node of a second current mirror circuit of the differential input stage and boost the charging operation of the output amplification stage according to a voltage difference between input and output voltages, and a second current source circuit for controlling current supply to an output node of a first current mirror circuit of the differential input stage and boost the discharging operation of the output amplification stage.

主权项

1. An output circuit comprising:
a differential input stage; an output amplification stage; an amplification boost circuit; an input terminal; an output terminal; and first to fifth power supply terminals, wherein the first differential pair includes: a first differential pair having a transistor pair that inputs therein an input signal of the input terminal and an output signal of the output terminal in a differential mode; a first current source for driving the first differential pair; a first current mirror including a transistor pair of a first conductivity type that is coupled between the first power supply terminal and first and second nodes and receives an output current of the first differential pair; a second current mirror including a transistor pair of a second conductivity type that is coupled between the second power supply terminal and third and fourth nodes; a first floating current source circuit coupled between the second node to which an input of the first current mirror is coupled and the fourth node to which an input of the second current mirror is coupled; and a second floating current source circuit coupled between the first node to which an output of the first current mirror is coupled and the third node to which an output of the second current mirror is coupled; wherein the output amplification stage includes: a first transistor of the first conductivity type that is coupled between the third power supply terminal and the output terminal and whose control terminal is coupled to the first node; and a second transistor of the second conductivity type that is coupled between the fourth power supply terminal and the output terminal and whose control terminal is coupled to the third node; wherein the amplification boost circuit includes: a second differential pair having a transistor pair that inputs therein an input signal of the input terminal and an output signal of the output terminal in a differential mode, and second and third current sources coupled to the fifth power supply terminal, and wherein when a voltage difference between the output voltage of the output terminal and a voltage of the fifth power supply terminal is larger than a previously set first value as compared with a voltage difference between the input voltage of the input terminal and the voltage of the fifth power supply terminal, the amplification boost circuit deactivates the third current source according to an output of one transistor of the transistor pair whose input is coupled to the output terminal in the second differential pair, activates the second current source according to an output of the other transistor of the transistor pair whose input is coupled to the input terminal in the second differential pair, and combines a current from the second current source to either current of an input current inputted to the first floating current source circuit or a current outputted from the first floating current source circuit, wherein when the voltage difference between the input voltage of the input terminal and the voltage of the fifth power supply terminal is larger than a previously set second value as compared with the voltage difference between the output voltage of the output terminal and the voltage of the fifth power supply terminal, the amplification boost circuit deactivates the second current source according to an output of the other transistor of the transistor pair whose input is coupled to the input terminal in the second differential pair, activates the third current source according to an output of the one transistor of the transistor pair whose input is coupled to the output terminal in the second differential pair, and combines a current from the third current source to either current of a current inputted into the second floating current source circuit or a current outputted from the second floating current source circuit, and wherein when the voltage difference between the output voltage of the output terminal and the voltage of the fifth power supply terminal is less than or equal to the first value as compared with the voltage difference between the input voltage of the input terminal and the voltage of the fifth power supply terminal and, at the same time, the voltage difference between the input voltage of the input terminal and the voltage of the fifth power supply terminal is less than or equal to the second value as compared with the voltage difference between the output voltage of the output terminal and the voltage of the fifth power supply terminal, the amplification boost circuit controls switching so that both of the second and third current sources are deactivated.