Bidirectional Level Shifter Circuit for Polycrystalline TFT Driving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional level shifters in display devices, particularly in polycrystalline thin film transistor (TFT) flat panel displays, require additional complementary circuits to shift input voltage in both directions, limiting their operational efficiency due to high threshold voltage and low electric field effect mobility.
Innovation Solution
A level shifter design that includes a signal conversion unit generating output signals with the same phase as the input signals but with higher and lower voltages, and an amplifying unit producing a third output signal with greater amplitude, utilizing transistor-capacitor combinations to achieve voltage adjustments without the need for complementary circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional level shifter is used to increase or decrease input voltage, then voltage level conversion is achieved, but additional complementary circuits are required to shift voltage in both directions
Solution Approach 1:
The patent combines the functions of voltage increase and voltage decrease into a single level shifter circuit. The signal conversion unit integrates multiple conversion circuits that can selectively output either increased voltage (first output signal) or decreased voltage (second output signal) based on control signals, eliminating the need for separate complementary level shifters.
Solution Approach 2:
The level shifter is designed as a multi-functional device that can perform both voltage elevation and voltage reduction operations through a single circuit. The signal conversion unit responds to different control signals to selectively generate output signals with either increased or decreased voltage levels, making the circuit universal for bidirectional voltage shifting.
2Productivity
If polycrystalline TFTs with high threshold voltage and low electric field effect mobility are used, then integration of driving units is achieved, but higher voltage than input voltage is required for stable high-speed driving
Solution Approach 1:
The patent changes the voltage parameter by using signal conversion circuits that generate output signals with different voltage levels than the input signal. The conversion circuits adjust the voltage amplitude to provide sufficiently large voltage swing for rapid transistor switching, enabling high-speed operation of polycrystalline TFT driving units.
3Device complexity
If a single operation level shifter is used, then circuit simplicity is maintained, but only unidirectional voltage shifting is possible
Solution Approach 1:
The level shifter employs dynamic control through control signals that selectively activate different conversion circuits within the signal conversion unit. Based on the state of control signals, the circuit dynamically switches between generating increased voltage outputs and decreased voltage outputs, enabling bidirectional voltage shifting without requiring separate static circuits for each direction.
Data Source
AI summary
A level shifter includes; a level conversion unit which receives a first input signal and a second input signal, wherein the second input signal is an inversion of the first input signal, and generates a first output signal having substantially a same phase of the first input signal and a voltage which is higher than the first input signal and a second output signal having substantially a same phase as the first input signal and a voltage which is lower than the first input signal; and wherein the level shifter further includes an amplifying unit which receives the first and second output signals and generates a third output signal having substantially a same phase as the first input signal and an amplitude which is greater than the first input signal.