Sample-and-Hold Sensor Interface for Low-Power ADC Operation
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Solution Overview
Problem
Semiconductor devices face challenges in reducing power consumption, particularly due to high consumption current in A/D converter circuits and difficulties in setting these circuits to a non-operation period for long durations, which affects accuracy and longevity in sensor-equipped signal processing devices.
Innovation Solution
A semiconductor device structure incorporating a sample-and-hold circuit with oxide semiconductor transistors that retain analog signals, allowing intermittent operation of the A/D converter circuit and extended battery life, while maintaining signal accuracy across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the A/D converter circuit operates continuously to maintain signal accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic operation of the A/D converter circuit by alternating between a first control period (sampling phase) and a second control period (A/D conversion phase). During the first control period, the sample-and-hold circuit captures analog signals while the A/D converter remains inactive. During the second control period, the A/D converter processes the held signals. This periodic alternation allows the A/D converter to operate intermittently rather than continuously, significantly reducing power consumption while maintaining measurement accuracy through the sample-and-hold circuit's signal retention capability.
2Use of energy by moving object
If the A/D converter circuit is set to non-operation period for long time to reduce power consumption, then power consumption is reduced, but signal accuracy deteriorates
Solution Approach 1:
The patent introduces a sample-and-hold circuit as an intermediary component between the sensor and the A/D converter circuit. This intermediary holds the analog signal at a stable voltage level during the A/D converter's non-operation periods, preventing signal degradation. The sample-and-hold circuit captures the analog signal during the first control period and maintains it during the second control period when the A/D converter is inactive, thereby preserving signal accuracy even when the A/D converter operates intermittently to reduce power consumption.
3Measurement precision
If multiple sampling is performed to increase accuracy, then measurement precision is improved, but the A/D converter circuit must operate for every multiple sampling which increases power consumption
Solution Approach 1:
The patent implements periodic operation of the A/D converter circuit by alternating between a first control period (sampling phase) and a second control period (A/D conversion phase). During the first control period, the sample-and-hold circuit captures analog signals while the A/D converter remains inactive. During the second control period, the A/D converter processes the held signals. This periodic alternation allows the A/D converter to operate intermittently rather than continuously, significantly reducing power consumption while maintaining measurement accuracy through the sample-and-hold circuit's signal retention capability.
Solution Approach 2:
The patent performs preliminary sampling action during the first control period where the sample-and-hold circuit captures and holds the analog signal before the A/D converter operates. This preliminary action prepares the signal in advance, allowing the A/D converter to process multiple sampled values during its active period without needing to operate continuously for each individual sampling event, thus reducing overall power consumption while maintaining accuracy.
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
The solution enables low power consumption, prolonged driving, and high accuracy in sensor signal processing, even under significant temperature changes, by switching between sampling and A/D conversion periods to minimize power usage and maintain signal integrity.
Implementation Method 1
a sample-and-hold circuit that retains the output signal of the amplifier circuit as an analog voltage
Data Source
AI summary
A semiconductor device with a novel structure is provided. The semiconductor device includes a sensor, an amplifier circuit to which a sensor signal of the sensor is input, a sample-and-hold circuit that retains a voltage corresponding to an output signal of an amplifier input to the sample-and-hold circuit, an analog-to-digital converter circuit to which an output signal of the sample-and-hold circuit corresponding to the voltage is input, and an interface circuit. The interface circuit has a function of switching and controlling a first control period in which the sensor signal is input to the amplifier circuit and an output signal of the amplifier circuit is retained in the sample-and-hold circuit and a second control period in which a digital signal obtained by output of the voltage retained in the sample-and-hold circuit to the analog-to-digital converter circuit is output to the interface circuit. In the first control period, the analog-to-digital converter circuit is switched to stop output of the digital signal. The first control period is longer than the second control period.