Sequential Charge Readout for Higher-Resolution Sensor A/D Conversion
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Solution Overview
Problem
The resolution of charge stored in sensor elements is limited by the bit width of the operational amplifier in existing sensor drive circuits, necessitating an improvement in A/D conversion resolution to produce more accurate digital signals.
Innovation Solution
Incorporating a control circuit that partially and sequentially reads charges from sensor elements, using an A/D converter with an integrator to convert each partially read charge, thereby enhancing the A/D resolution beyond the limitations of the operational amplifier's bit width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bit width of the operational amplifier in the A/D converter is increased to improve resolution, then the measurement precision of charge increases, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent divides the charge reading process into multiple sequential stages, where a switch partially reads the charge from the sensor element in steps. By segmenting the charge into multiple smaller portions and converting each portion separately, the system achieves higher effective resolution without requiring a higher-bit operational amplifier. The control circuit coordinates multiple read operations to reconstruct the full charge value from partial measurements.
Solution Approach 2:
The patent employs periodic read operations where the switch sequentially reads charge portions at different time intervals. The control circuit manages multiple periodic conversion cycles, accumulating results from each cycle to build the final high-resolution digital signal. This temporal segmentation allows the system to achieve resolution beyond the operational amplifier's native bit width.
2Measurement precision
If multiple partial reads are performed to increase A/D resolution, then the measurement precision improves, but the reading time increases
Solution Approach 1:
The patent performs preliminary partial reads of the charge in controlled stages before final conversion. The control circuit预先 (in advance) manages the switching sequence to read charge portions systematically, preparing intermediate results that are then combined to form the complete high-resolution measurement. This preliminary staged reading optimizes the overall conversion efficiency.
Solution Approach 2:
The patent maintains continuous useful action by overlapping the partial read operations with conversion processes. While one charge portion is being read, the system prepares for the next portion's conversion, ensuring minimal idle time. The control circuit coordinates the continuous flow of read-convert-read-convert operations, maximizing the utilization of the A/D converter and reducing total measurement time.
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 configuration effectively increases the A/D resolution by integrating multiple conversions, allowing for a higher bit representation of charges stored in sensor elements, such as from 3-bit to 5-bit or 10-bit to 16-bit, depending on the operational amplifier's bit width and number of conversions.
Implementation Method 1
a sensor element including a photoelectric conversion element that generates an electric charge according to incident light
Implementation Method 2
using an A/D converter with an integrator to convert each partially read charge, thereby enhancing the A/D resolution beyond the limitations of the operational amplifier's bit width
Data Source
AI summary
According to one embodiment, a sensor device includes a switch, a control circuit and an A/D converter. The switch is connected to a sensor element configured to store charge and provided to read the charge stored in the sensor element from the sensor element. The control circuit is configured to control the switch so as to partially and sequentially read the charge stored in the sensor element. The A/D converter is connected to the switch, which is configured to output a digital signal obtained by A/D-converting an analog signal according to the charge, for each charge partially read via the switch.