Same-Polarity Transistor Driver Circuit for Low-Power Output Swing
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Solution Overview
Problem
Semiconductor display devices with driver circuits composed of transistors of the same conductivity type face issues with increased power consumption and decreased amplitude of potential output due to transistors being normally on, leading to wasted current and higher power consumption.
Innovation Solution
Incorporating a configuration with a first transistor for controlling power supply potential and a second transistor for controlling clock signal potential, along with a circuit for controlling electrical connections between the transistors and power supply wirings, allowing for independent control of gate voltage to turn off the transistors when necessary, reducing power consumption and maintaining output amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transistors of the same conductivity type are used in driver circuits, then manufacturing cost is reduced, but power consumption increases and output amplitude decreases due to transistors being normally on
Solution Approach 1:
The patent applies parameter changes by adjusting the threshold voltage of transistors through controlled formation of gate insulating films and semiconductor layers. Specifically, the gate insulating film is formed with specific thickness (50-200 nm) and the semiconductor layer is doped with specific concentrations to achieve desired threshold voltage characteristics, allowing transistors to be turned off properly even when normally on, thus reducing power consumption while maintaining same-conductivity-type configuration
Solution Approach 2:
The patent implements preliminary action by pre-configuring the transistor threshold voltages during manufacturing to ensure proper on/off control. The gate insulating film and semiconductor layer are formed with specific properties beforehand, and doping is performed in advance to set appropriate threshold voltages, enabling the transistors to function correctly as switches without requiring additional control circuits
2Ease of manufacture
If transistors of the same conductivity type are used in driver circuits, then manufacturing cost is reduced, but output amplitude decreases due to wasted current
Solution Approach 1:
The patent changes physical parameters of the transistor structure, specifically the gate insulating film thickness (50-200 nm) and semiconductor layer doping concentration, to achieve optimal threshold voltage values. This ensures that transistors can be fully turned off, preventing wasted current and maintaining proper output amplitude while using transistors of the same conductivity type
3Power
If channel width of transistors is increased to provide large current supply capability, then current supply capability is improved, but power consumption increases due to wasted current
Solution Approach 1:
The patent optimizes the channel width and doping concentration parameters to achieve the desired current supply capability while minimizing power consumption. By carefully controlling the doping concentration in the semiconductor layer and the gate insulating film thickness, the transistor can provide sufficient current when on while maintaining low leakage current when off, thus achieving high current supply capability without excessive power consumption
Data Source
AI summary
A semiconductor device includes first and second transistors having the same conductivity type and a circuit. One of a source and a drain of the first transistor is electrically connected to that of the second transistor. First and third potentials are supplied to the circuit through respective wirings. A second potential and a first clock signal are supplied to the others of the sources and the drains of the first and second transistors, respectively. A second clock signal is supplied to the circuit. The third potential is higher than the second potential which is higher than the first potential. A fourth potential is equal to or higher than the third potential. The first clock signal alternates the second and fourth potentials and the second clock signal alternates the first and third potentials. The circuit controls electrical connections between gates of the first and second transistors and the wirings.