Patent ID: 9437145
Filing Date: 2016-09-06
CPC Classification: G09G

Claim Text:
1. A gamma reference voltage generating circuit used to provide a gamma reference voltage for a source driver; the gamma reference voltage comprising a positive gamma reference voltage and a negative gamma reference voltage; the gamma reference voltage generating circuit comprising: a center voltage generation unit configured to generate a center voltage; a gamma reference voltage generation unit configured to generate the positive gamma reference voltage and the negative gamma reference voltage, and control the positive gamma reference voltage and the negative gamma reference voltage to be symmetrical with respect to the center voltage; a first voltage divider unit comprising a first terminal for receiving the positive gamma reference voltage and a second terminal for receiving the center voltage; the first voltage divider unit being configured to divide a voltage between the positive gamma reference voltage and the center voltage; and a second voltage divider unit comprising a first terminal for receiving the center voltage, and a second terminal for receiving the negative gamma reference voltage; the second voltage divider unit being configured to divide a voltage between the center voltage and the negative gamma reference voltage, wherein the gamma reference voltage generation unit comprises: a first voltage follower comprising an input terminal for receiving a test voltage, and an output terminal coupled with the first terminal of the first voltage divider unit; a first negative feedback operational amplifier comprising a positive input terminal for receiving the center voltage, an inverting input terminal for receiving the test voltage through an input resistor, an output terminal coupled with the inverting input terminal of the first negative feedback operational amplifier through a feedback resistor; the output terminal of the first negative feedback operational amplifier coupled with the second terminal of the second voltage divider unit; wherein the positive gamma reference voltage and the negative gamma reference voltage are controlled to be symmetrical with respect to the center voltage by adjusting resistance values of the input resistor and the feedback resistor.