IC Current Sensing Using Matched Paths for PVT Compensation
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Solution Overview
Problem
Integrated circuits (ICs) face challenges in efficiently detecting and managing current variations due to component variations from manufacturing processes, voltage supply, and temperature changes, particularly in applications like USB power delivery, where different devices require varying power sourcing capabilities.
Innovation Solution
A system within an IC chip that includes a power switch circuit and a current detection circuit, utilizing a sense circuit path to match process, voltage supply, and temperature variations, with a comparator to compare voltage drops across both paths and provide a data signal for current detection, eliminating the need for external resistive elements and ensuring high accuracy without additional input pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensing circuit is implemented to detect current variations, then current detection accuracy is improved, but the circuit becomes sensitive to component variations from manufacturing processes, voltage supply, and temperature changes
Solution Approach 1:
The patent creates a replica of the power circuit path as a sense circuit path, with matching transistors and conductive traces. This copy experiences identical PVT variations, allowing the variations to be differentialled out during comparison, thus maintaining measurement accuracy despite component variations
Solution Approach 2:
The comparator continuously compares the voltage drops between the power circuit path and sense circuit path, providing feedback that compensates for PVT variations. This feedback mechanism dynamically adjusts for component variations, maintaining reliable current detection across different operating conditions
2Ease of operation
If external resistive elements are used for current sensing, then current detection is simplified, but additional input pins and increased device complexity are required
Solution Approach 1:
The patent merges the current sensing function with the existing power switch circuit by using the same conductive traces and transistors for both power delivery and current sensing. This integration eliminates the need for separate external resistors and additional input pins, reducing device complexity while maintaining sensing capability
Solution Approach 2:
The power circuit path components serve dual purposes: they conduct power during normal operation and simultaneously serve as the sensing elements for current detection. This multi-functionality eliminates the need for dedicated sensing components, simplifying the overall device architecture
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 solution enables accurate current detection and limiting in ICs, effectively compensating for component variations, ensuring reliable power delivery and preventing overcurrent conditions, while maintaining low costs and high integration levels.
Implementation Method 1
A comparator circuit can be configured to compare a voltage drop across the power circuit path to a voltage drop across the sense circuit path
Implementation Method 2
The first transistor is configured with first on-resistance value and the second transistor is configured with a second on-resistance value and wherein a ratio of the first and second resistance values to the first on-resistance value is substantially equal to a ratio of the third and fourth resistance values to the second on-resistance value
Data Source
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AI summary
A system can provide current detection in an integrated circuit (IC) chip while compensating for variations in circuit components resulting from process, voltage supply, temperature, or combinations thereof. The system can include the IC chip that has a power switch circuit that includes a power circuit path including a first transistor connected to a power source through a first conductive trace that has a first resistance value, and to a load by a second conductive trace having a second resistance value. A current detection circuit is configured to compensate for the variations in the power switch circuit using a sense circuit path that is configured to match process, voltage supply, and temperature variations in the power circuit path.