Logarithmic Current Measurement Circuit for 1 mA to 100 A Range
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Solution Overview
Problem
Existing current measurement circuits struggle to reliably measure currents over a wide range, particularly from 1 mA to 100 A.
Innovation Solution
A circuit utilizing logarithmic amplifiers, electromagnetic interference filters, comparators, and analog-to-digital converters to expand the measurable current range, allowing accurate measurement from 1 mA to 100 A.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amplifiers are used for current measurement, then the circuit structure is simple, but the measurable current range is limited and cannot reliably measure currents from 1 mA to 100 A
Solution Approach 1:
The current measurement range is divided into multiple segments: a first measurement range handled by a first logarithmic amplifier and a second measurement range handled by a second logarithmic amplifier. Each amplifier is optimized for its specific range, enabling reliable measurement across the entire 1 mA to 100 A spectrum while maintaining manageable circuit complexity through modular design
Solution Approach 2:
The circuit dynamically switches between different logarithmic amplifiers based on the input current magnitude. A selection mechanism activates the appropriate amplifier (first for lower currents, second for higher currents) to ensure optimal measurement reliability across the full dynamic range without requiring a single complex amplifier design
2Adaptability or versatility
If a single logarithmic amplifier is used to expand measurement range, then the measurable current range increases, but measurement precision decreases across different current levels
Solution Approach 1:
Different logarithmic amplifiers are designed with optimized characteristics for specific current ranges. The first logarithmic amplifier is optimized for precision in the lower current range (1 mA to moderate levels), while the second logarithmic amplifier is optimized for the higher current range (moderate to 100 A). This local optimization ensures high measurement precision within each segment while maintaining broad adaptability across the full range
Solution Approach 2:
The system dynamically selects which logarithmic amplifier to use based on the input current level, ensuring that the measurement is always performed by the amplifier best suited for that specific current range. This dynamic selection mechanism preserves measurement precision across the entire 1 mA to 100 A spectrum
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
The circuit effectively measures currents from 1 mA to 100 A with enhanced accuracy and reliability, overcoming the limitations of conventional amplifiers.
Implementation Method 1
a first logarithmic amplifier adapted to convert the current into a first voltage
Data Source
AI summary
The present disclosure relates to a first circuit for measuring a first current, the first circuit including a current step-down circuit, a logarithmic comparator circuit, and a differential voltage amplifier circuit. A first input of the current step-down circuit is configured to receive the first current, and a first output of the current step-down circuit is configured to provide a ratiometric step-down current to a first logarithmic amplifier via a current mirror assembly. The logarithmic comparator circuit includes the first logarithmic amplifier, configured to convert the ratiometric step-down current into a logarithmic first voltage, and a second logarithmic amplifier, configured to provide a logarithmic reference voltage. The differential voltage amplifier circuit is configured to compare the logarithmic first voltage with the logarithmic reference voltage.