Versatile Current Sensor Integrator for Switching Regulator
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Solution Overview
Problem
Current switching converters face challenges in accurately sensing both positive and negative currents due to limited bandwidth and offset currents, which degrade accuracy and restrict detection to only positive currents.
Innovation Solution
Implementing a current sensor with an integrator that calculates the average voltage and includes both positive and negative current sensing, eliminating the need for reference voltage or current, and using a configuration with high and low side pass devices, subtractor, and sample/hold circuits to achieve high accuracy current monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filtering is used to obtain averaged sense current, then the sense current accuracy is improved, but the frequency bandwidth is limited
Solution Approach 1:
The patent applies periodic action by using a low-pass RC filter to periodically average the sense current over time. The filter continuously integrates the high-frequency switching current components, producing a smoothed averaged sense current that maintains accuracy while eliminating the need for wide bandwidth operation. This periodic filtering approach resolves the contradiction by achieving accurate averaged current measurement without requiring the op-amp to respond to high-frequency variations.
2Ease of operation
If reference voltage or current is used to generate sense current, then the operating point is established, but offset current is created that degrades accuracy
Solution Approach 1:
The patent extracts and eliminates the reference voltage/current components that cause offset current. By removing the traditional reference-based biasing scheme, the invention achieves sense current generation without the harmful offset current that degrades measurement accuracy. The sense current is instead generated directly from the switching converter operation itself, taking out the problematic reference elements from the system.
Solution Approach 2:
The patent implements self-service by enabling the sense current to be generated autonomously from the switching converter's own operation without external reference voltage or current. The sensing mechanism uses the natural voltage drops and current flows within the switching converter topology to create the sense current signal, making the system self-sufficient and eliminating reference-dependent offset errors.
3Device complexity
If only positive current detection is implemented, then the circuit simplicity is maintained, but the versatility is limited
Solution Approach 1:
The patent applies universality by designing a sense current generation mechanism that simultaneously handles both positive and negative current detection. The low-pass RC filter and sense current generation circuit are configured to process bidirectional current flows, enabling the same circuit topology to measure current in both directions without requiring separate detection paths. This multi-functional approach resolves the contradiction by maintaining circuit simplicity while achieving versatile bidirectional current sensing capability.
Data Source
AI summary
A preferred implementation of a switching converter with a versatile current sensor is achieved, by adding an integrator for instant sense current in the switching converter. The integrator calculates the average current of the switching converter and includes both positive and negative current sensing. The current sensor's response time is determined by the integrator coefficient and therefore not limited by the bandwidth of the current sensor. Performance degradation in the current sensor due to offset current is removed and the current sensor does not require a voltage reference or a current reference. High accuracy current monitoring and current sensing is achieved without an external sense device. The integrator of the current sensor serves to boost the gain of the switching converter.