Display Driver Sequential Circuits with Low-Duty Pulse Control
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Solution Overview
Problem
Variations in transistor threshold voltage in sequential circuits of driver circuits lead to failures in outputting desired signals, preventing proper image display and increasing manufacturing costs.
Innovation Solution
A semiconductor device comprising specific transistor configurations and capacitors with controlled pulse signals, including transistors with overlapping gates and low-duty ratio signals, to stabilize transistor thresholds and reduce voltage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistors are used in sequential circuits with conventional configurations, then the circuit can be fabricated using standard processes, but variations in threshold voltage lead to unreliable signal output
Solution Approach 1:
The patent applies parameter changes by modifying the transistor gate structure to include multiple gates (first gate and second gate) with different functions. The first gate controls the main current flow while the second gate independently adjusts the threshold voltage, allowing precise control of transistor characteristics to compensate for manufacturing variations and ensure reliable signal output.
Solution Approach 2:
The patent introduces a capacitor as an intermediary element connected to the gate of the transistor. This capacitor stores and releases charge to stabilize the gate voltage, acting as a mediator that compensates for threshold voltage variations and ensures consistent transistor operation despite manufacturing tolerances.
2Area of stationary object
If driver circuits are formed over the same substrate as pixel portions to narrow bezels, then manufacturing cost is reduced and bezel width is narrowed, but transistor threshold voltage variations increase
Solution Approach 1:
The patent modifies the transistor parameters by implementing a multi-gate structure where the second gate can independently adjust the threshold voltage. This allows compensation for the increased threshold voltage variations that occur when transistors are fabricated on the same substrate as pixel portions, ensuring reliable sequential circuit operation while maintaining the narrowed bezel design.
Solution Approach 2:
The patent implements a feedback mechanism where the second gate of the transistor receives control signals that adjust the threshold voltage based on the operating conditions. This feedback control compensates for threshold voltage variations caused by co-fabrication with pixel portions, maintaining reliable signal output in the integrated driver circuit.
3Reliability
If conventional transistor configurations are used in sequential circuits, then device complexity is low, but output signal reliability deteriorates due to threshold voltage variations
Solution Approach 1:
The patent changes the structural parameters of the transistor by adding a second gate, which increases device complexity but enables precise control of threshold voltage. This additional gate allows the circuit to compensate for variations and reliably output pulse signals, trading increased structural complexity for improved signal reliability.
Data Source
AI summary
A highly reliable semiconductor device is provided. The semiconductor device includes first to third transistors and a capacitor. In the first transistor, one of a source and a drain is supplied with a first signal, the other of the source and the drain is connected to a gate of the second transistor and one electrode of the capacitor, and a gate is supplied with a second pulse signal. In the second transistor, one of a source and a drain is supplied with a first pulse signal, and the other of the source and the drain is connected to the other electrode of the capacitor and one of a source and a drain of the third transistor. In the third transistor, the other of the source and the drain is supplied with the first potential, and a gate is supplied with a second signal that is an inverted signal of the first signal. The first pulse signal is a clock signal, and the second pulse signal has a duty ratio of 55% or lower.