| 摘要 |
PURPOSE: A decoding circuit for selecting tone voltage of a source driver of a thin film transistor liquid crystal display device is provided to offer a tone voltage decoder circuit a length direction size thereof is decreased by improving a layout of a tone voltage decoder circuit. CONSTITUTION: Sixty four kinds of tone voltage are connected to sixty four tone voltage terminals. The odd number tone voltage terminals(V1, V3, ...V63) are opposed to the even number tone voltage terminals(V2, V4, ..., V64) in both directions of a common output line(400). The odd number tone voltage terminals(V1, V3, ...V63) are connected to the first decoding unit(100), and the even number tone voltage terminals(V2, V4, ..., V64) are connected to the second decoding unit(300). The first decoding unit(100) consists of eight 4x1 decoders(1001, 1002, ..., 1008). The second decoding unit(300) consists of eight 4x1 decoders(3001, 3002, ..., 3008). One 4x1 decoder consists of 4x3 numbers transistor. The output terminals of the first decoding unit(100) and the second decoding unit(300) are connected to the third decoding unit in parallel. The third decoding unit consists of 16x3 numbers transistor. In the third decoding unit, the number of output terminals numbers of the first decoding unit(100) is eight, and the first 8x3 decoder block(200A) is composed by using 8x3 numbers transistors for selecting one tone voltage from the eight output terminals. The second 8x3 decoder block(200B) is composed by using the other 8x3 numbers transistors for selecting one tone voltage from eight output of the second decoding unit(300). The first 8x3 decoder block(200A) and the second 8x3 decoder block(200B) are opposed thereto in the both directions of the common output line(400).
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