Decoder Circuit Design for Faster Grayscale Voltage Selection
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Summary
Problems
Conventional decoder circuits for liquid crystal displays face issues with slow response times and failure to output selected analog grayscale voltages within the necessary time, especially when the voltage is low, due to reduced current flow, leading to display faults like bright or dark lines and irregular colors.
Innovation solutions
The introduction of a decoder circuit with a first and second selection circuit, where the first selection circuit operates in a substrate biased at a higher potential and the second selection circuit operates in a substrate biased at a lower potential, using p-channel and n-channel transistors respectively, to ensure quick propagation of both high and low grayscale voltages to the output terminal.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If PMOS transistors are used in a conventional decoder circuit, then the circuit can select analog grayscale voltages, but the response time becomes slow when selecting lower voltage levels due to reduced current flow
Why choose this principle:
The decoder circuit is segmented into two separate selection circuits: a first selection circuit for selecting higher grayscale voltages and a second selection circuit for selecting lower grayscale voltages. Each circuit uses transistors optimized for its specific voltage range, allowing both high and low voltage selections to achieve fast response times without the current flow limitations of a single PMOS-based circuit.
Principle concept:
If PMOS transistors are used in a conventional decoder circuit, then the circuit can select analog grayscale voltages, but the response time becomes slow when selecting lower voltage levels due to reduced current flow
Why choose this principle:
Different regions of the decoder circuit are assigned different transistor types with locally optimized characteristics. The first selection circuit uses PMOS transistors optimized for higher voltage selections, while the second selection circuit uses transistors with enhanced current driving capability for lower voltage selections. This local optimization ensures that each part of the circuit operates at peak efficiency for its specific function.
Application Domain
Data Source
AI summary:
The introduction of a decoder circuit with a first and second selection circuit, where the first selection circuit operates in a substrate biased at a higher potential and the second selection circuit operates in a substrate biased at a lower potential, using p-channel and n-channel transistors respectively, to ensure quick propagation of both high and low grayscale voltages to the output terminal.
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.