PCB Current Measurement via Resistance-Ratio Reference Traces
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Solution Overview
Problem
Current measurement methods for printed circuit boards, such as using shunts, incur additional costs, space requirements, weight, and are susceptible to aging, making them undesirable for current measurement in printed conductors.
Innovation Solution
A method and apparatus that utilize a predefined resistance ratio between two printed conductors on a circuit board, where a known current is injected into one conductor to measure the voltage drop, allowing the current in the other conductor to be determined based on the known ratio and measured voltages, with configurations to mitigate electromagnetic interference and thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shunts are used for current measurement, then current measurement is enabled, but additional costs, space requirements, weight, and susceptibility to aging increase
Solution Approach 1:
The patent extracts the measurement function from external shunt components and integrates it directly into the printed circuit board traces. By using the PCB traces themselves as both the current-carrying conductors and the measurement elements, the need for separate shunt components, additional soldered connections, and extra wiring is eliminated, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent makes the PCB traces serve dual functions: they act as both the current-carrying conductors for power/ground signals and as the measurement elements for current sensing. This multi-functionality eliminates the need for dedicated shunt components, reducing the overall number of components, space requirements, and weight while enabling current measurement without additional complexity
2Measurement precision
If shunts are used for current measurement, then current measurement is enabled, but space requirements and weight increase
Solution Approach 1:
The patent merges the current-carrying function and the measurement function into a single integrated structure - the PCB trace. By combining these functions in one element rather than using separate shunt components, the space required is dramatically reduced, as the measurement capability is embedded within the existing conductor geometry without requiring additional component mounting space
3Measurement precision
If shunts are used for current measurement, then current measurement is enabled, but susceptibility to aging increases
Solution Approach 1:
The patent enables the PCB traces to serve themselves by using the same conductor that carries the current to also perform the measurement function. This self-service approach eliminates the need for separate aging-prone shunt components, as the measurement is derived directly from the voltage drop across the trace itself, which is already part of the circuit and subject to the same environmental conditions but without additional failure points
4Device complexity
If current measurement is performed using voltage drop across printed conductor, then no additional components are needed, but measurement precision may be affected by electromagnetic interference and thermal effects
Solution Approach 1:
The patent introduces an asymmetric measurement approach by using a separate auxiliary trace with a known resistance ratio to the measurement trace. This asymmetric configuration allows for differential measurement techniques that can cancel out common-mode electromagnetic interference and thermal effects, thereby maintaining measurement precision without requiring additional symmetric component pairs
Solution Approach 2:
The patent employs feedback by using the measured voltage drop and the known resistance ratio to calculate and compensate for errors caused by electromagnetic interference and thermal effects. The system uses the relationship between the measurement trace and auxiliary trace to provide feedback information that enables correction of measurement inaccuracies, maintaining precision without additional active compensation components
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 provides a cost-effective, space-efficient, and less susceptible to aging method for current measurement in printed circuit boards, while effectively canceling out electromagnetic interference and thermal errors.
Implementation Method 1
A device for measuring a first electric voltage across the first printed conductor, by reference to the first electric current flowing in the first printed conductor
Implementation Method 2
A device for measuring a second electric voltage across the second printed conductor by reference to the predefined or known second electric current flowing in the second printed conductor
Data Source
AI summary
The present disclosure relates to an apparatus for measuring a first electric current in a first printed conductor of a printed circuit board, which also includes a second printed conductor, wherein the ratio of electrical resistances between the first and second printed conductors is known. The apparatus includes a device for measuring a first electric voltage across the first printed conductor based on the first electric current in the first printed conductor, a device for injecting a known second electric current into the second printed conductor, a device for measuring a second electric voltage across the second printed conductor based on the known second electric current in the second printed conductor, and a device for determining the first electric current based on the first electric voltage, the second electric voltage, the known second electric current and the known ratio of electrical resistances between the first and second printed conductors.