Charge Retention Circuit for Time Measurement
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Solution Overview
Problem
Existing time measurement technologies in electronic circuits face limitations such as limited measurable time range, electric stress on dielectrics, incompatibility with memory manufacturing, and the need for calibration tables for charge-to-time conversion.
Innovation Solution
A circuit design featuring a capacitive element with a dielectric leakage and a transistor with an isolated control terminal, utilizing two parallel branches with transistors of different types and a digital-to-analog converter for non-linear signal generation, allowing for residual charge reading without power and without the need for conversion tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a capacitive component with dielectric leakage is used for time measurement, then the circuit can operate without permanent power supply, but the measurable time range is limited by dielectric intervention possibilities
Solution Approach 1:
The time measurement function is segmented into two independent parts: charge storage (capacitive element) and charge reading (transistor with isolated control terminal). This segmentation allows the reading operation to be performed without disturbing the stored charge, enabling extended measurement ranges while maintaining low power consumption.
Solution Approach 2:
The transistor with isolated control terminal serves multiple functions: it acts as a switch for charge transfer, a buffer for charge isolation, and a readout device. This multi-functionality eliminates the need for separate circuit components, expanding the measurable time range without increasing circuit complexity or power consumption.
2Measurement precision
If the capacitive component charge is continuously monitored, then real-time time measurement is achieved, but electric stress on the dielectric increases causing measurement drift
Solution Approach 1:
Instead of continuous monitoring, the circuit uses periodic sampling where the charge is read only at specific intervals through the isolated control terminal. This periodic readout mechanism maintains measurement precision while significantly reducing the cumulative electric stress on the dielectric, preventing measurement drift over time.
Solution Approach 2:
The isolated control terminal of the transistor acts as an intermediary between the stored charge and the measurement circuit. It allows charge transfer for reading without creating direct electric stress on the dielectric, thereby maintaining measurement accuracy while minimizing dielectric degradation.
3Reliability
If a specific capacitive component structure is formed for time measurement, then charge retention is improved, but compatibility with memory manufacturing steps is reduced
Solution Approach 1:
The time measurement circuit is merged with memory cell structures, using the same manufacturing steps and materials. The capacitive element and transistor with isolated control terminal are integrated into standard memory fabrication processes, achieving both reliable charge retention and manufacturing compatibility without requiring separate production lines.
Solution Approach 2:
The circuit design uses universal components and manufacturing techniques that are already established in memory production. By making the time measurement circuit compatible with existing memory manufacturing steps, the same facilities can produce both memory devices and time measurement devices, improving ease of manufacture while maintaining charge retention reliability.
4Measurement precision
If calibration tables are used for charge-to-time conversion, then measurement accuracy is improved, but device complexity and calibration steps increase
Solution Approach 1:
The transistor with isolated control terminal enables the circuit to perform self-calibration by comparing the stored charge against known reference states. This self-service mechanism eliminates the need for external calibration tables, reducing device complexity while maintaining measurement precision through automated charge-to-time conversion.
Solution Approach 2:
The mechanical approach of using lookup tables for charge-to-time conversion is replaced with an electronic measurement method using the isolated control terminal. This substitution eliminates the need for stored calibration data structures, reducing device complexity while achieving accurate time measurement through direct charge proportionality.
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 reliable and reproducible time measurement over extended periods without power supply, compatible with memory technologies, and facilitates fast programming and calibration, enhancing measurement accuracy and compatibility.
Implementation Method 1
measuring the charge of a capacitive component exhibiting a leakage from its dielectric spacer
Implementation Method 2
capacitive component exhibiting a leakage from its dielectric spacer
Data Source
AI summary
A method and a circuit for reading an electronic charge retention element for a temporal measurement, of the type including at least one capacitive element whose dielectric exhibits a leakage and a transistor with insulated control terminal for reading the residual charges, the reading circuit including; two parallel branches between two supply terminals, each branch including at least one transistor of a first type and one transistor of a second type, the transistor of the second type of one of the branches consisting of that of the element to be read and the transistor of the second type of the other branch receiving, on its control terminal, a staircase signal, the respective drains of the transistors of the first type being connected to the respective inputs of a comparator whose output provides an indication of the residual voltage in the charge retention element.