Shielded Capacitive Elements for High-Speed A/D Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analog-to-digital converters in robots with solid-state imaging devices face accuracy issues due to variations in capacitance values caused by parasitic capacitances and manufacturing misalignments, which hinder high-speed imaging capabilities.
Innovation Solution
The design includes a comparison circuit with capacitive elements having a predetermined capacitance ratio, where the second electrodes of these elements are shielded between the first and third electrodes to reduce parasitic capacitances, and a selection circuit configuration that maintains the capacitance ratio accuracy, enabling high-speed A/D conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the capacitance value of capacitive elements is reduced to achieve higher conversion rate, then the A/D conversion speed increases, but the influence of parasitic capacitance increases and conversion accuracy deteriorates
Solution Approach 1:
The patent introduces a shielding electrode that converts the harmful parasitic capacitance effect into a beneficial shielding effect. The shielding electrode is positioned between the first electrode and the second electrode of the capacitive element, creating a shielded structure that reduces the influence of external parasitic capacitance on the A/D conversion accuracy while maintaining the reduced capacitance value for high-speed conversion.
Solution Approach 2:
The shielding electrode acts as an intermediary element between the capacitive elements and the external environment. This intermediate structure isolates the capacitive elements from external electromagnetic interference and parasitic capacitance sources, thereby improving conversion accuracy without sacrificing conversion speed.
2Loss of time
If the capacitance value of capacitive elements is reduced to decrease sampling time, then the imaging speed increases, but the A/D conversion accuracy deteriorates due to increased parasitic capacitance influence
Solution Approach 1:
The shielding electrode structure converts the harmful effect of parasitic capacitance into a beneficial shielding effect, enabling the use of reduced capacitance values for faster sampling while maintaining accuracy through the protective shielding mechanism.
Solution Approach 2:
The shielding electrode serves as an intermediary protective layer that allows the capacitive elements to operate at reduced capacitance values for fast sampling, while the shielding structure mediates the interaction with external parasitic capacitance sources to maintain conversion accuracy.
3Measurement precision
If the capacitance ratio between capacitive elements is maintained for accuracy, then the A/D conversion precision improves, but the device complexity increases due to additional shielding structures
Solution Approach 1:
The capacitive element is segmented into multiple distinct components: a first electrode, a second electrode, and a shielding electrode positioned between them. This segmentation allows each component to perform its specific function independently - the first and second electrodes maintain the capacitance ratio for accuracy, while the shielding electrode reduces parasitic capacitance influence, thereby achieving high precision without excessive overall complexity.
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 enhances A/D conversion accuracy, reduces sampling and conversion times, and supports high-speed imaging in robots by minimizing the influence of parasitic capacitances and manufacturing errors.
Implementation Method 1
capacitive elements each of which has a first end connected to the first terminal of the comparison circuit via a first line, and includes: a first to an m-th capacitive element (where m is an integer of 2 or more) that each have a predetermined capacitance ratio
Implementation Method 2
a second electrode disposed between the first electrode and the third electrode, above the semiconductor substrate, to oppose the first electrode and the third electrode and electrically connected to the first end
Data Source
AI summary
An analog-to-digital converter includes: a first to an (m+1)-th capacitive element each of which has a first end connected to a first terminal of a comparison circuit and have a predetermined capacitance ratio; and selection circuits which are connected to second ends of the capacitive elements, respectively. Each of the capacitive elements includes: a first electrode disposed in a semiconductor substrate and electrically connected to the second end; a third electrode disposed above the semiconductor substrate to oppose the first electrode and electrically connected to the second end; a second electrode disposed between the first electrode and the third electrode, above the semiconductor substrate, and electrically connected to the first end; a first insulation film disposed between the first and second electrodes; and a second insulation film disposed between the third and second electrodes.