Unipolar TFT Logic Circuits With Full Swing and Low Static Power
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Solution Overview
Problem
Conventional unipolar thin-film transistors (TFTs) in SRAMs and DFFs experience high static power consumption due to diode configurations, leading to increased fabrication costs and limited output swing, making them unsuitable for cost-effective implementation in flexible electronics.
Innovation Solution
The use of low-power electronic components with unipolar TFTs, featuring a static leakage current reduction through innovative circuit designs that eliminate direct current paths between VDD and VSS, utilizing bootstrapped logic and complementary read ports, and employing a single type of TFTs (n-type or p-type) to achieve full output swing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If unipolar TFTs are used in conventional diode configurations, then fabrication cost is reduced and device simplicity is improved, but static power consumption increases significantly
Solution Approach 1:
The patent implements dynamic control of transistor states through clocked operation, where transistors are alternately switched between on and off states based on clock phases. This dynamic approach allows the circuit to achieve full output swing while maintaining low static power consumption, as transistors are not permanently in high-leakage states as in conventional diode configurations.
Solution Approach 2:
The patent changes the operational parameters of unipolar TFTs by implementing bootstrapped gate control and controlled voltage switching. By dynamically adjusting gate voltages and utilizing capacitive coupling, the circuit achieves complementary-like behavior from unipolar devices, reducing static leakage while maintaining full output swing capability.
2Device complexity
If unipolar TFTs are used in diode configurations, then device complexity is reduced, but output swing is limited
Solution Approach 1:
The patent introduces capacitive coupling elements and bootstrapped gate structures as intermediary components between the unipolar TFTs and the output nodes. These intermediaries enable voltage boosting and signal regeneration, allowing the circuit to achieve full output swing (0 to VDD) without requiring complementary transistor pairs, thus maintaining low device complexity.
3Use of energy by moving object
If complementary TFTs are fabricated to reduce static leakage, then power consumption is reduced, but fabrication cost increases
Solution Approach 1:
The patent segments the transistor operation into distinct clock phases, where different transistors are activated in sequence rather than simultaneously. This temporal segmentation allows unipolar TFTs to perform functions that would traditionally require complementary pairs, achieving low power consumption without the need for complex complementary fabrication processes.
Solution Approach 2:
The patent employs periodic clock signals to control the operation of unipolar TFTs, creating alternating periods of high and low impedance states. This periodic control enables the circuit to achieve low static power consumption by ensuring that leakage paths are periodically blocked, eliminating the need for expensive complementary TFT fabrication.
4Device complexity
If unipolar TFTs are used with direct current paths, then circuit simplicity is improved, but static leakage current increases
Solution Approach 1:
The patent transforms static direct current paths into dynamically controlled signal paths using clocked operation. Transistors are switched between on and off states based on clock phases, creating time-varying impedance that blocks static leakage while allowing dynamic signal transmission. This maintains circuit simplicity while eliminating the harmful static leakage current.
Data Source
AI summary
Low-power electronic components are disclosed, fabricated using a single type of unipolar thin-film transistor (uTFT), such as n-type or p-type devices. The components include logic structures such as static random-access memory (SRAM), data flip-flops (DFFs), and latches, and are particularly suited for use in flexible or display-integrated electronics. Each logic structure comprises a logic core coupled to external power, ground, and optionally control signal lines via two or more fabrics of uTFT-based switching elements. The arrangement avoids direct-current conduction paths between VDD and VSS, or other external lines such as word lines or bit lines. The result is a class of uTFT logic circuits with reduced static power consumption, even in the absence of complementary transistor types. Applications include system-on-panel designs, flexible displays, wearable sensors, and ultra-low-power IoT devices.