Semiconductor Device Sample-and-Hold Circuit Intermittent Operation
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Solution Overview
Problem
Semiconductor devices with built-in batteries face challenges in maintaining long-term operation due to low battery charging frequency and temperature variations, which affect the accuracy of digital signals in analog-to-digital converter circuits.
Innovation Solution
A semiconductor device structure incorporating a sample-and-hold circuit with signal retention circuits and a control circuit that utilizes oxide semiconductor transistors to retain analog voltages during battery power supply periods and output them during external power supply periods, allowing for intermittent operation and improved temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the battery charging frequency is reduced to extend operation time, then the duration of action is improved, but the analog voltage retention accuracy deteriorates due to temperature variations
Solution Approach 1:
The patent divides the signal retention function into multiple independent signal retention circuits (first, second, third circuits), each capable of holding analog voltage separately. This segmentation allows the system to maintain signal integrity even when operating intermittently with reduced battery charging frequency, as each circuit can independently preserve its portion of the signal without being affected by temperature variations during idle periods.
Solution Approach 2:
The patent performs preliminary action by retaining the analog voltage in the signal retention circuits before the A/D conversion period begins. The control circuit stores the sensor output signals as analog voltages in advance during periods when power is not being actively consumed, so that when power is supplied for A/D conversion, accurate digital signals can be generated without requiring continuous power supply or frequent battery charging.
2Use of energy by moving object
If the semiconductor device operates intermittently with reduced power consumption, then the use of energy is improved, but the analog voltage retention capability deteriorates due to transistor characteristic variations
Solution Approach 1:
The patent applies local quality by using oxide semiconductor transistors specifically in the signal retention circuits where analog voltage holding is critical, while other parts of the device can use different transistor types. The oxide semiconductor transistors provide locally enhanced temperature stability and lower off-state current precisely where needed for signal retention, allowing intermittent operation with maintained reliability.
Solution Approach 2:
The patent employs composite materials by using oxide semiconductor as the channel formation region material in the transistors within the signal retention circuits. This oxide semiconductor layer is combined with gate electrodes and insulating layers to create a composite transistor structure that exhibits superior temperature stability and lower leakage current compared to conventional transistors, enabling reliable analog voltage retention during intermittent operation with reduced power consumption.
3Measurement precision
If multiple signal retention circuits are used to maintain signal accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the signal retention circuits with identical structures using oxide semiconductor transistors, where each circuit performs the same function of retaining analog voltage from sensor outputs. This standardized multi-functionality allows the system to achieve improved signal accuracy through parallel retention circuits while managing complexity through repetition of proven design modules rather than creating unique complex circuits for each retention function.
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
Enables extended operation time under low battery charging frequency and maintains signal accuracy across varying temperatures by using oxide semiconductor transistors with low off-state current and stable electrical characteristics.
Implementation Method 1
the transistors included in the signal retention circuits each include a semiconductor layer including an oxide semiconductor in a channel formation region
Data Source
AI summary
Provided is a semiconductor device with a novel structure in which the power consumption can be reduced. The semiconductor device includes a sensor, a sample-and-hold circuit to which a sensor signal of the sensor is input, an analog-digital converter circuit to which an output signal of the sample-and-hold circuit is input, a control circuit, a battery, and an antenna. The sample-and-hold circuit includes a first selection circuit, a plurality of signal retention circuits, and a second selection circuit, and the control circuit performs a control so that a potential corresponding to the sensor signal is retained in the plurality of signal retention circuits successively by the first selection circuit in a first period during which power is supplied from the battery, and performs a control so that the output signal based on the potential retained in the plurality of signal retention circuits is output by the second selection circuit in a second period during which power is supplied from outside through the antenna.