Semiconductor Current-Sensing Circuit With Ultra-Low Off-State Leakage
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Solution Overview
Problem
Existing sensors face challenges in accurately measuring minute currents due to the reduction in sensor size, necessitating improved circuit designs for precise current reading.
Innovation Solution
A semiconductor device incorporating a transistor with a metal oxide in the channel formation region and an operational amplifier, with an off-state current less than or equal to 1.0×10−12 A, capable of measuring minute currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If sensor size is reduced, then device miniaturization is achieved, but current output becomes minute and measurement accuracy deteriorates
Solution Approach 1:
The patent changes the electrical parameters of the transistor by using metal oxide semiconductor material with specific properties (low off-state current, adjustable threshold voltage) to enable accurate measurement of minute currents while maintaining miniaturized sensor size
Solution Approach 2:
The patent employs composite material structure combining metal oxide semiconductor in the channel region with silicon-based operational amplifier, creating a hybrid device that leverages the low leakage current property of metal oxide for precise minute current measurement
2Device complexity
If conventional transistors are used, then device simplicity is maintained, but off-state current is too high for minute current measurement
Solution Approach 1:
The patent modifies the transistor's material composition parameter by replacing conventional silicon channel with metal oxide semiconductor channel, fundamentally changing the electrical characteristics to achieve ultra-low off-state current while keeping the basic transistor structure intact
3Device complexity
If threshold voltage is not controlled, then device simplicity is maintained, but measurement stability at varying temperatures deteriorates
Solution Approach 1:
The patent implements feedback control by connecting the operational amplifier's output to its inverting input, creating a negative feedback loop that stabilizes the threshold voltage and compensates for temperature variations, ensuring measurement stability
Solution Approach 2:
The operational amplifier serves multiple functions: it provides threshold voltage control, temperature compensation, and current-to-voltage conversion, reducing the need for separate dedicated circuits and maintaining device simplicity
Data Source
AI summary
A semiconductor device capable of measuring a minute current is provided. The semiconductor device includes an operational amplifier and a diode element. An inverting input terminal of the operational amplifier and an input terminal of the diode element are electrically connected to a first terminal to which current is input, and an output terminal of the operational amplifier and an output terminal of the diode element are electrically connected to a second terminal from which voltage is output. A diode-connected transistor that includes a metal oxide in a channel formation region is used as the diode element. Since the off-state current of the transistor is extremely low, a minute current can flow between the first terminal and the second terminal. Thus, when voltage is output from the second terminal, a minute current that flows through the first terminal can be estimated from the voltage.