Decoder circuit
AssigneeOki Electric Industry Co., Ltd.
InventorYasutaka Takabayashi
Life of this patent
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Abstract
A decoder circuit that selects a grayscale voltage responsive to digital input includes a first transistor circuit that selects grayscale voltages greater than a certain voltage and a second transistor circuit that selects grayscale voltages less than the certain voltage. The two transistor circuits are formed in separate substrates, one substrate being a well formed in the other substrate, or both substrates being wells formed in a third substrate. The substrate of the first transistor circuit is biased at a higher potential than the substrate of the second transistor circuit. This biasing scheme enables all selected grayscale voltages to propagate quickly through the decoder circuit.
Claims18
A decoder circuit having a plurality of grayscale voltage input terminals for receiving respective grayscale voltages, a plurality of digital signal input terminals receiving respective bit signals, and an output terminal, the grayscale voltages being divided into a first group and a second group, each of the grayscale voltages in the first group being higher than all of the grayscale voltages in the second group, the decoder circuit comprising:
- a first selection circuit having a plurality of transistors interconnected to select one of the grayscale voltages in the first group according to the bit signals and conduct the selected grayscale voltage to the output terminal;
- and
- a second selection circuit having a plurality of transistors interconnected to select one of the grayscale voltages in the second group responsive to the bit signals and conduct the selected grayscale voltage to the output terminal;
- wherein
- the transistors in the first selection circuit operate in a first substrate biased at a first potential and the transistors in the second selection circuit operate in a second substrate biased at a second potential lower than the first potential.
Dependencies are inferred from the claim text.