High-Side Current Detection Circuit With Offset and Gain Calibration
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Solution Overview
Problem
Existing high-side current detection circuits suffer from detection errors due to transistor mismatches, resistor process errors, and operational amplifier input offsets, which cannot be effectively calibrated for varying load currents.
Innovation Solution
The proposed high-side current detection circuit incorporates a gain calibration circuit and an offset compensation circuit to separate and calibrate the detection errors into fixed offset errors and dynamic gain errors, effectively eliminating errors under different load currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing high-side current detection circuits are used, then the circuit structure is simple, but detection errors occur due to transistor mismatch, resistor process error, and operational amplifier input offset
Solution Approach 1:
The patent segments the detection error into two distinct components: offset error (fixed component) and gain error (variable component). This segmentation allows each error type to be calibrated independently through separate calibration circuits, improving measurement precision without requiring complete circuit redesign. The offset calibration circuit addresses fixed errors while the gain calibration circuit handles variable errors across different load conditions.
Solution Approach 2:
The patent implements preliminary calibration actions before actual current detection. The offset calibration circuit performs initial error compensation by adjusting the operational amplifier's input offset voltage, while the gain calibration circuit pre-establishes the correct gain relationship. These preliminary calibration actions eliminate detection errors before measurement begins, ensuring high accuracy from the start.
2Adaptability or versatility
If single-point calibration is performed to compensate detection errors, then the calibration process is simple, but new detection errors occur when load current changes
Solution Approach 1:
The patent transforms the static single-point calibration into a dynamic multi-point calibration system. The gain calibration circuit continuously adjusts the gain based on the actual load current, making the calibration adaptive to varying operating conditions. This dynamic adjustment ensures that the detection accuracy is maintained across the entire load current range, not just at a single calibration point.
Solution Approach 2:
The patent changes the calibration parameters from fixed single-point values to variable multi-point values. The gain calibration circuit modifies the gain parameter according to different load current levels, while the offset calibration circuit adjusts the offset parameter to compensate for fixed errors. These parameter changes enable the circuit to adapt to varying load conditions while maintaining high measurement precision.
Data Source
AI summary
A calibration method includes obtaining an offset error of the overcurrent protection circuit by changing a current limiting state of the overcurrent protection circuit, adjusting an offset compensation circuit to calibrate the offset error of the overcurrent protection circuit and adjusting a gain calibration circuit based on the current limiting state of the overcurrent protection circuit to calibrate a gain error of the overcurrent protection circuit, wherein the overcurrent protection circuit comprises a first transistor, a second transistor, a third transistor, a first operational amplifier, a gain calibration circuit, an offset compensation circuit, and a driving circuit, and wherein the driving circuit is configured to receive a signal generated by the gain calibration circuit and generate a gate drive signal applied the first transistor and the third transistor.