Patent ID: 8736642
Filing Date: 2014-05-27
Classification: G09G

Abstract:
1. An offset reduction output circuit for a source driver adapted to receive a gray scale voltage corresponding to gray scales represented by digital data and to generate a driving voltage to be supplied to a liquid display panel, the offset reduction output circuit comprising: an operational amplifier having a non-inverting input terminal, an inverting input terminal and an output terminal, said non-inverting input terminal being adapted to receive a reference voltage; a first input capacitor having one terminal and opposite terminal; a first output capacitor having one terminal and opposite terminal, said one terminal of the first input capacitor and said one terminal of the first output capacitor being coupled to a first node connected to the inverting input terminal of the operational amplifier in at least a normal output operation; and a first switching circuit for shorting said one terminal of the first input capacitor to said opposite terminal of the first input capacitor and for shorting said one terminal of the first output capacitor to said opposite terminal of the first output capacitor in a reset operation so that the reference voltage is applied to said one and opposite terminals of the first input capacitor and to said one and opposite terminals of the first output capacitor, and for applying the gray scale voltage to said opposite terminal of the first input capacitor and for connecting an opposite terminal of the first output capacitor to the output terminal of the operational amplifier in the normal output operation after the reset operation, wherein the first switching circuit includes a first switch device and a second switch device connected with each other in series at a connection point, the first and second switch devices are connected between the first node and the output terminal of the operational amplifier, turned on in the reset operation, and turned off in the normal output operation, and wherein the reference voltage is applied to the connection point of the first and second switch devices in the normal output operation.