Capacitance Measurement via Natural Discharge and Constant Current
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Solution Overview
Problem
Existing memory systems face challenges in accurately measuring the capacitance value of capacitors, particularly in solid-state drives, which affects the reliability of power loss protection and data storage, as age-related capacitance degradation can lead to insufficient energy for backup operations.
Innovation Solution
A memory system that includes a nonvolatile semiconductor memory, a capacitor, a constant current circuit, a measurement circuit, and a controller, which measures capacitance by combining natural discharge and constant current measurements to account for leakage current, allowing for accurate calculation of capacitance values and detection of leakage resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only constant current measurement is used to measure capacitance, then the measurement process is simple, but the measurement precision is insufficient due to leakage current
Solution Approach 1:
The measurement process is divided into two distinct phases: a first period for natural discharge measurement and a second period for constant current measurement. By segmenting the measurement into these phases, the system can separately capture the effects of leakage current and capacitance, then combine the data to achieve high-precision capacitance measurement while managing complexity through structured temporal separation.
Solution Approach 2:
The natural discharge measurement is performed in advance during the first period before the constant current measurement in the second period. This preliminary action allows the system to characterize the leakage current behavior beforehand, which is then used to correct and refine the capacitance measurement in the subsequent constant current phase, improving overall measurement precision.
2Reliability
If capacitance measurement does not account for leakage current, then the measurement is faster, but the reliability of capacitance value is insufficient
Solution Approach 1:
The measurement system continuously monitors the capacitor voltage throughout both the natural discharge period and the constant current measurement period without interruption. This continuous observation allows the system to capture complete discharge characteristics and leakage current effects, ensuring reliable capacitance measurement while optimizing the total measurement duration through efficient continuous data collection.
Solution Approach 2:
The system changes the measurement parameters by switching between two distinct measurement modes: natural discharge mode in the first period where no external current is applied, and constant current extraction mode in the second period. By varying the current parameter over time and analyzing the voltage response in both regimes, the system reliably separates leakage current effects from true capacitance, achieving accurate measurements.
3Reliability
If leakage current is not considered in capacitance measurement, then the product life prediction is shorter, but unexpected failures due to short-circuit defects can occur
Solution Approach 1:
The measurement system uses feedback from the natural discharge phase to inform and adjust the constant current measurement phase. By continuously monitoring voltage changes during natural discharge and using this information to guide the constant current extraction process, the system achieves accurate capacitance measurement that accounts for leakage current, leading to more reliable product life predictions and reduced risk of unexpected failures.
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 approach enables precise capacitance measurement, extending the predicted product life of the memory system by considering leakage current, preventing unexpected failures due to short-circuit defects, and ensuring reliable data protection during power loss.
Implementation Method 1
a capacitor (140), which stores charge to be supplied to the nonvolatile semiconductor memory (120)
Implementation Method 2
The constant current circuit (10) extracts the charge from the capacitor (140) with a constant current
Implementation Method 3
The measurement circuit (20) measures a terminal voltage at of the capacitor (140)
Implementation Method 4
a change in the measured terminal voltage over time in each of a first period during which the capacitor naturally discharges
Data Source
AI summary
According to one or more embodiments, a memory system includes a nonvolatile semiconductor memory, a capacitor, a constant current circuit, a measurement circuit, and a controller. The capacitor stores charges to be supplied to the nonvolatile semiconductor memory. The constant current circuit extracts the charge from the capacitor at a constant current. The measurement circuit measures a terminal voltage of the capacitor. The controller controls the nonvolatile semiconductor memory. The controller calculates a capacitance value of the capacitor based both on a resistance value of a leakage resistance of the capacitor and a change in the measured terminal voltage over time in each of a first period during which the capacitor naturally discharges and a second period during which the constant current circuit extracts the charge from the capacitor.