Current Measurement Circuit Using Alternating Branch Capacitors
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Solution Overview
Problem
Existing current measurement circuits in electronic circuits face limitations in measuring current accurately and rapidly due to the constraints of analog-to-digital converters (ADCs), which restricts the granularity of measurement and prevents effective tracking of output current in power converters like buck or boost converters.
Innovation Solution
A current measurement circuit utilizing two circuit branches with capacitors that alternately accumulate charge and convert it into voltages, which are then digitized by an ADC, allowing for more accurate and rapid measurement of average current over a specific interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single circuit branch is used for current measurement, then the circuit structure is simple, but the measurement precision and continuity are insufficient due to ADC conversion speed limitations
Solution Approach 1:
The measurement circuit is divided into multiple parallel circuit branches (first circuit branch with first capacitor, second circuit branch with second capacitor). Each branch independently accumulates charge and generates voltage, allowing the ADC to sequentially convert voltages from different branches. This segmentation enables continuous current measurement with higher precision while managing complexity through modular structure.
Solution Approach 2:
The control circuit alternately selects different circuit branches in periodic cycles. During each cycle, the ADC converts the voltage from one branch, then switches to the next branch. This periodic switching between branches allows the system to maintain continuous measurement capability while the ADC operates at its conversion speed, effectively resolving the contradiction between measurement precision and ADC speed limitations.
2Productivity
If ADC conversion speed is increased to improve measurement granularity, then measurement precision improves, but the cost and complexity of the ADC increases
Solution Approach 1:
The circuit branches perform preliminary charge accumulation during dedicated time periods before ADC conversion. The capacitors integrate the current signal over time, pre-processing the measurement data in the analog domain. This preliminary action allows the ADC to work at lower speeds while still achieving high measurement granularity, as the integration effect captures fine details that would require faster sampling otherwise.
Solution Approach 2:
Capacitors serve as intermediary elements between the current signal and the ADC. Instead of directly converting high-speed current variations, the capacitors transform the current into voltage through charge accumulation, acting as a buffer that smooths the signal for slower ADC conversion. This intermediary approach maintains measurement granularity while reducing ADC speed requirements.
3Speed
If continuous current tracking is implemented, then the ability to track current transients improves, but the measurement system becomes more complex and slower due to ADC limitations
Solution Approach 1:
Multiple circuit branches operate in parallel, with the control circuit ensuring that at least one branch is always actively accumulating charge. While the ADC converts voltage from one branch, another branch continues the measurement function. This continuous operation across multiple branches maintains the ability to track current transients without interruption, achieving speed and continuity while managing complexity through coordinated multi-branch operation.
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 more accurate and continuous current measurement, even with larger loads, by leveraging analog accumulation and alternating branch operation to overcome ADC conversion speed limitations, effectively tracking current transients and providing precise digital values indicative of the measured current.
Implementation Method 1
a first capacitor that may be coupled to the output node by the closing of a first switch... the first capacitor accumulating charge and thus generating a first voltage
Data Source
AI summary
A current measurement circuit is disclosed. The current measurement circuit includes first and second circuit branches coupled to a circuit node through which current is to be measured. During a first period, the first circuit branch converts the current into a first voltage. During a second period, the second circuit branch converter the current into a second voltage. An analog-to-digital converter is configured to convert the first and second voltages into digital values indicative of the measured current. A control circuit is configured to alternately select one of the first and second branches during the generation of the digital values.