D/A conversion circuit and semiconductor device

Year	Description
1998	Invention patented by Jun Koyama, Mitsuaki Osame, Yukio Tanaka, Munehiro Azami, Naoko Yano, and Shou Nagao on November 22th, 1998. Abstract: A D/A conversion circuit with a small area is provided. In the D/A conversion circuit, according to a digital signal transmitted from address lines of an address decoder, one of four gradation voltage lines is selected. A circuit including two N-channel TFTs is connected in series to a circuit including two P-channel TFT, and a circuit including the circuits connected in series to each other is connected in parallel to each of the gradation voltage lines. Further, an arrangement of the circuit including the two N-channel TFTs and the circuit including the two P-channel TFTs is reversed for every gradation voltage line. By this, the crossings of wiring lines in the D/A conversion circuit becomes small and the area can be made small.
2000	Invention patented by Shou Nagao on May 14th, 2000. Abstract: A DAC whose area is held down and a semiconductor device using the DAC are fabricated. A D/A conversion circuit is disclosed, including n resistors A.sub.0, A.sub.1, . . . A.sub.n-1, n resistors B.sub.0, B.sub.1, . . . , B.sub.n-1, two power-supply voltage lines, a power-supply voltage line L and a power-supply voltage line H, maintained at potentials different from each other, n switches SWa.sub.0, SWa.sub.1, . . . , SWa.sub.n-1, n switches SWb.sub.0, SWb.sub.1, . . . , SWb.sub.n-1, and an output line, wherein, by n-bit digital signals inputted from the outside, said n switches SWa.sub.0, SWa.sub.1, . . . , SWa.sub.n-1 and said n switches SWb.sub.0, SWb.sub.1, . . . , SWb.sub.n-1 are controlled, and, from the output line, an analog gradation voltage signal is outputted.
2000	Invention patented by Yukio Tanaka on August 13th, 2000. Abstract: A D/A conversion circuit in accordance with the present invention, which is provided with a switch swD, allows a writing operation of a voltage (a true gradation voltage) to be performed at a higher speed by first applying a first voltage (a voltage close to the true gradation voltage), which is supplied without passing through a resistor element, to an output line and then applying a second voltage (the true gradation voltage), which is supplied via the resistor element, to the output line. Thus, the present invention can provide a D/A conversion circuit capable of writing display data to liquid crystal cells with higher precision at higher speed, and a semiconductor device utilizing such a D/A conversion circuit.
2001	Invention patented by Yukio Tanaka on December 27th, 2001. Abstract: A D/A conversion circuit in accordance with the present invention, which is provided with a switch swD, allows a writing operation of a voltage (a true gradation voltage) to be performed at a higher speed by first applying a first voltage (a voltage close to the true gradation voltage), which is supplied without passing through a resistor element, to an output line and then applying a second voltage (the true gradation voltage), which is supplied via the resistor element, to the output line. Thus, the present invention can provide a D/A conversion circuit capable of writing display data to liquid crystal cells with higher precision at higher speed, and a semiconductor device utilizing such a D/A conversion circuit.
Source: selected by the editor from original sources.

D/A conversion circuit and semiconductor device

Invention: D/A conversion circuit and semiconductor device