Integrated Circuit Current Shunt Amplifier with Temperature-Matched Gain Resistor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current sensing amplifiers face challenges in accurately sensing current through printed circuit board (PCB) conductors without requiring complex circuitry, temperature-sensing elements, and external digitization, especially when using copper trace conductors as shunt resistors, which are impractical due to high conductivity and space requirements.
Innovation Solution
An integrated circuit current sensing amplifier with a gain resistor having a similar temperature coefficient to the shunt resistor, allowing for automatic and instant temperature compensation, eliminating the need for external temperature sensors and digitization, and utilizing a copper gain resistor to reduce the physical size and cost of the shunt resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a section of copper trace conductor is used as a shunt resistor, then the physical size and cost are reduced, but the resistance is insufficient due to high conductivity of copper
Solution Approach 1:
The patent changes the resistance parameter by using a serpentine configuration of the copper trace, transforming a low-resistance straight trace into a high-resistance winding structure. This allows the same copper material to provide sufficient resistance for accurate current sensing while maintaining the benefits of using copper (low cost, small size, high conductivity).
Solution Approach 2:
The patent applies curvature by configuring the copper trace in a serpentine or winding pattern instead of a straight line. This geometric transformation increases the effective resistance of the trace without requiring additional materials or larger PCB area, thereby enabling accurate voltage drop measurement across the shunt resistor.
2Measurement precision
If a conventional current sensing amplifier is used with a copper shunt resistor, then temperature compensation is required, but complex circuitry and external digitization are needed
Solution Approach 1:
The patent uses homogeneous materials for both the shunt resistor and the gain resistor (both made from copper or copper alloy). This ensures that both resistors have matching temperature coefficients, allowing the amplifier to automatically compensate for temperature variations without requiring external temperature sensors or complex digital processing.
Solution Approach 2:
The system performs self-temperature-compensation through the inherent properties of the homogeneous resistive materials. The amplifier automatically adjusts for temperature effects using the matched temperature coefficients of the copper-based resistors, eliminating the need for external temperature sensing elements or microcontroller-based compensation algorithms.
3Measurement precision
If temperature-sensing elements and external digitization are used, then temperature compensation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the external temperature sensing elements and digital processing requirements from the system. By using homogeneous copper-based resistors with matched temperature coefficients, the temperature compensation function is achieved through the inherent material properties rather than through separate sensing and processing components, thereby simplifying manufacturing.
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 accurate, low-cost current sensing and voltage measurement across PCB conductors with simplified temperature compensation, reducing the need for complex circuitry and external processing, while minimizing the physical size and cost of the shunt resistor.
Implementation Method 1
The gain resistor RG has a temperature coefficient which is essentially the same as that of the shunt resistor RSHUNT
Data Source
AI summary
An integrated circuit current shunt amplifier (2A) includes an amplifier (9) having a (+) input connected to a first terminal (5A) of a shunt resistor (RSHUNT). An output transistor (24) has a gate coupled to an output of the amplifier, a source coupled to a (−) input of the amplifier, and a drain coupled to a first terminal of an output resistor (ROUT). A gain resistor (RGAIN) is coupled between the (−) input of the amplifier and a second terminal of the shunt resistor. The gain resistor has a temperature coefficient which is essentially the same as that of the shunt resistor.A voltage regulator (26) can be coupled between the second terminal of the shunt resistor and a low-side supply voltage terminal (27) of the amplifier. A charge pump (30) can provide a below-ground voltage on a second terminal of the output resistor. A difference amplifier (31) coupled to the drain and referenced to the below-ground voltage produces an output voltage (Vout) referenced to ground.