Display Decoder Back-Gate Biasing for Wider Output Voltage Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing decoder circuits for display devices face challenges in extending the voltage range of output signals and controlling the threshold voltage of transistors effectively, leading to increased manufacturing costs and area requirements due to the need for additional masks and processes to adjust threshold voltage levels.
Innovation Solution
A decoder architecture that includes first and second sub-decoders receiving non-overlapping reference voltage groups, with each sub-decoder comprising switches with back gates supplied by distinct power supply voltages, allowing for selective output of reference voltages based on digital signals and enabling control of threshold voltage through back gate voltage adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the voltage range of output signals is extended by adjusting transistor threshold voltages, then the output voltage range is improved, but the manufacturing cost increases due to additional masks and processes
Solution Approach 1:
The patent changes the back gate voltage parameter dynamically to control the threshold voltage of transistors. By supplying different back gate voltages (first back gate voltage for first sub-decoder, second back gate voltage for second sub-decoder), the threshold voltage is adjusted without requiring additional manufacturing masks or processes, thus extending the output voltage range while avoiding increased manufacturing cost
Solution Approach 2:
The patent implements dynamic control of transistor threshold voltage through dynamic back gate voltage supply. The back gate voltage is changed based on the selected reference voltage group, allowing the decoder to adaptively extend its output voltage range. This dynamic parameter adjustment eliminates the need for static manufacturing modifications, resolving the contradiction between versatility and ease of manufacture
2Adaptability or versatility
If the threshold voltage of transistors is reduced to extend voltage range, then the voltage range is improved, but the gate size and area of transistors increase
Solution Approach 1:
The patent uses back gate voltage as a control parameter to adjust transistor threshold voltage dynamically. By changing the back gate voltage rather than modifying the physical gate size, the patent achieves extended voltage range while maintaining compact transistor dimensions, thus resolving the contradiction between voltage range and transistor area
3Adaptability or versatility
If additional masks and processes are used to control threshold voltage, then the voltage range is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex manufacturing process modifications with simple electrical parameter control. Instead of using additional masks and fabrication steps to adjust threshold voltage, the patent achieves the same effect by dynamically changing the back gate voltage through existing circuitry, thus improving voltage range control while avoiding increased device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution extends the voltage range of output signals, reduces the gate size and area of transistors, and allows for flexible adjustment of threshold voltage without additional manufacturing steps, thereby reducing costs and improving decoder performance.
Implementation Method 1
A substrate bias effect will be briefly explained. As described in standard textbooks, the threshold voltage of a MOS transistor for a substrate voltage VBS is given by the following expression (1)
Data Source
AI summary
Disclosed is a decoder, receiving the first and the second reference voltage groups and selecting a reference voltage in accordance with a received digital signal, including a first sub-decoder receiving the first reference voltage group, a second sub-decoder receiving the second reference voltage group 20B, and a third sub-decoder receiving a reference voltage selected by the second sub-decoder and outputting the selected reference voltage to the first sub-decoder or an output terminal of the decoder. The first sub-decoder includes a transistor of a first conductivity type having a back gate supplied with a first power supply voltage, the second sub-decoder includes a transistor of the first conductivity type having a back gate supplied with a second power supply voltage, and the third sub-decoder includes a transistor of the first conductivity type having a back gate supplied with a first power supply voltage. The first power supply voltage is a first reference voltage, which is a most spaced from the second voltage section among the first reference voltage group, or a predetermined voltage even further spaced from the second voltage section than the first reference voltage. The second power supply voltage is a predetermined voltage within a range from a second reference voltage, which is a voltage closest to the first voltage section among the second reference voltage group, to a voltage within the first voltage section but not reaching the first reference voltage.