Temperature-Compensated Current Sensing for Power FET Circuits
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Solution Overview
Problem
Current sensing circuits in power converter circuits face inaccuracies due to differing temperature coefficients of field-effect transistors (FETs), which affect the accuracy of current measurement and efficiency of power converter operations.
Innovation Solution
Incorporating a temperature compensation circuit that adjusts for the temperature coefficients of FETs within the current sensing circuit, using a temperature circuit to compensate for differences in resistance changes among FETs, thereby improving the accuracy of current sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current sensing circuit uses FETs to measure current in power converter circuits, then the circuit can operate at different power supply voltage levels and perform various power management functions, but the measurement accuracy deteriorates due to differences in temperature coefficients between FETs
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference current based on temperature variations. The temperature compensation circuit monitors temperature and modifies the reference current parameter to counteract temperature coefficient differences in FETs, thereby maintaining accurate current sensing across varying temperature conditions while preserving adaptability to different voltage levels
Solution Approach 2:
The patent implements feedback through a temperature compensation circuit that continuously monitors temperature and adjusts the reference current accordingly. This closed-loop feedback mechanism detects temperature changes and automatically compensates for their effect on FET temperature coefficients, resolving the contradiction between measurement precision and operational adaptability
2Device complexity
If the current sensing circuit does not compensate for temperature coefficients, then the device complexity remains low, but the measurement precision deteriorates due to temperature variations affecting FET characteristics
Solution Approach 1:
The patent introduces an intermediary temperature compensation circuit that mediates between the temperature variations and the current sensing operation. This intermediary circuit generates a compensation signal based on temperature and injects it into the sensing path, adding minimal complexity while significantly improving measurement precision by canceling out temperature-induced errors
Solution Approach 2:
The patent uses parameter changes by adjusting the reference current parameter in response to temperature variations. This simple parameter adjustment approach maintains low device complexity while improving measurement precision, as it requires only modifying an electrical parameter rather than adding complex hardware structures
Data Source
AI summary
A current sensing circuit includes a first field-effect transistor (FET) coupled to a first current source, an inductor, and a power FET, and includes a second FET coupled to a second current source. The current sensing circuit also includes a temperature circuit coupled to the first FET and the second FET. The temperature circuit is configured to compensate for one or more differences between one or more temperature coefficients of one or more of the first FET, the second FET, and the power FET.