Two-Wire Oxide Semiconductor Logic Circuit for Stable Low-Power Operation
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Solution Overview
Problem
In logic circuits composed only of n-channel transistors, there is a drop in the threshold voltage of the output voltage, leading to increased power consumption due to shoot-through current. Additionally, silicon transistors experience changes in electrical characteristics at high temperatures, reducing the on/off ratio and compromising normal circuit operation.
Innovation Solution
A semiconductor device is designed with a configuration that includes multiple transistors and wiring connections, utilizing metal oxide transistors in the channel formation region. This configuration includes specific connections between the transistors' sources, drains, gates, and back gates to control current flow and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a logic circuit is composed of only n-channel transistors, then the circuit can be simplified in structure, but the threshold voltage drops and shoot-through current increases leading to higher power consumption
Solution Approach 1:
The patent divides the transistor structure into two independent gate control systems: a conventional gate and a back gate. This segmentation allows separate control of the channel, enabling independent optimization of threshold voltage and current flow characteristics without requiring complex circuit-level changes
Solution Approach 2:
The patent changes the electrical parameters of the transistor by introducing back gate voltage control. By adjusting the back gate voltage, the threshold voltage can be dynamically tuned and the channel conductivity can be modulated, thereby reducing shoot-through current and power consumption while maintaining circuit simplicity
2Ease of operation
If silicon transistors are used, then the device can operate at standard conditions, but electrical characteristics change at high temperatures reducing the on/off ratio
Solution Approach 1:
The patent utilizes the back gate to dynamically adjust the transistor's electrical parameters including threshold voltage and subthreshold slope. This parameter control compensates for temperature-induced variations, maintaining stable on/off ratios across different temperature conditions
Solution Approach 2:
The back gate mechanism provides a feedback control pathway where the threshold voltage can be adjusted in response to operating conditions including temperature. This allows the transistor to self-correct electrical characteristic drift caused by thermal effects
Data Source
AI summary
A semiconductor device capable of stable operation with low power consumption is provided. A logic circuit having a circuit configuration using a transistor including an oxide semiconductor in a channel formation region is included. The logic circuit is a two-input/two-output two-wire logic circuit. Transistors included in the logic circuit each include a gate and a back gate. An input terminal is electrically connected to one of a gate and a back gate of a transistor electrically connected to a wiring for supplying a high power supply potential. An output terminal is connected to the other of the gate and the back gate of the transistor electrically connected to the wiring for supplying a high power supply potential. An output terminal is electrically connected to one of a source and a drain of a transistor electrically connected to a wiring for supplying a low power supply potential. A gate or a back gate of the transistor electrically connected to the wiring for supplying a low power supply potential is electrically connected to an input terminal.