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Digital-to-analog converter and its source driver chip

A source driver chip and digital analog technology, applied in the direction of digital analog converters, etc., can solve problems such as abnormal screen display, inability to transmit data in real time, and increased time constant

Active Publication Date: 2016-06-22
NOVATEK MICROELECTRONICS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] However, with the improvement of resolution, the number of transistors on the transmission path increases, so that the on-resistance on the transmission path also increases, and the transmission time becomes longer. Real-time transmission of data, resulting in abnormal screen display
Taking the N-type digital-to-analog converter 208 as an example, when the number of N-type transistors on the transmission path increases, and the negative polarity Gamma voltage increases while the overdrive voltage decreases (such as the negative polarity Gamma voltage closest to the intermediate voltage VDDA / 2 VN[n] and its transmission path N1), at this time, the on-resistance of the unit N-type transistor increases, and the number of series on-resistance on the transmission path also increases, so that the time constant on the transmission path increases, resulting in signal failure timely output

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  • Digital-to-analog converter and its source driver chip
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  • Digital-to-analog converter and its source driver chip

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Embodiment Construction

[0040] Please refer to Figure 3A and Figure 3B , Figure 3A and Figure 3B It can be replaced by the embodiment of the present invention Figure 2A Partial circuit diagrams of a P-type DAC 306 and an N-type DAC 308 among the P-type DAC 206 and N-type DAC 208 . The P-type DAC 306 is partially similar to the P-type DAC 206 , so components and signals with similar functions are denoted by the same symbols. The main difference between the P-type DAC 306 and the P-type DAC 206 is to receive the positive gamma voltage VP[ that is closest to the intermediate voltage VDDA / 2 among the positive gamma voltages VP[0]˜VP[n]. n] (that is, the minimum value of the positive gamma voltages VP[0] to VP[n]), a transmission path P2 corresponding to a receiving end is compared with the positive gamma voltage VP[ under the same source-gate voltage difference. 0] to VP[n-1] have lower on-resistance; similarly, the N-type digital-to-analog converter 308 receives the closest negative polarity g...

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Abstract

The invention discloses a digital-to-analog converter used in a source driver chip of a liquid crystal display, comprising an output terminal for outputting an output voltage; multiple receiving terminals for receiving multiple gamma voltages; and A plurality of transmission paths respectively include a plurality of first-type transistors coupled between the plurality of receiving ends and the output end, and are used for outputting one of the plurality of gamma voltages as the plurality of gamma voltages according to a digital selection signal. Output voltage; wherein, a first transmission path corresponding to a first receiving terminal receiving a first gamma voltage closest to an intermediate voltage among the plurality of gamma voltages is relatively large under the same source-gate voltage difference The other transmission paths in one transmission path have lower on-resistance.

Description

technical field [0001] The present invention relates to a digital to analog converter (digital to analog converter, DAC) and its source driver chip, especially to a digital to analog converter and its Source driver chip. Background technique [0002] Generally speaking, in a source driver chip of a liquid crystal display, a digital to analog converter (digital to analog converter, DAC) will select an appropriate gamma voltage (Gamma voltage) from multiple gamma voltages to output to the output stage according to a digital selection signal. Grayscale display with properly driven panel. Among them, in order to avoid using the same polarity voltage (such as positive polarity or negative polarity) to continuously drive the liquid crystal molecules, and reduce the polarization or refraction effect of the liquid crystal molecules on the light, resulting in deterioration of the quality of the picture display, so the known technology has disclosed that the Gamma The magma voltage ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03M1/66
Inventor 程智修黄如琳洪邦桢
Owner NOVATEK MICROELECTRONICS CORP