Charge Pump Output Current Estimation Without Sense Resistor Loss
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Solution Overview
Problem
Accurately measuring the output current of switched capacitor power conversion circuits is complex due to efficiency losses from sense resistor power loss and calibration challenges, especially in integrated circuits where parasitic resistance varies and noise affects measurement accuracy.
Innovation Solution
Estimating the output current using the formula IOUT=(IIN×N)−Offset, where IOUT is the estimated output current, IIN is the measured input current, N is the multiplication or division factor, and Offset is an output current offset, allowing for internal estimation within the integrated circuit without direct measurement of output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of output current using sense resistor is implemented, then measurement accuracy is improved, but power loss increases due to sense resistor power loss
Solution Approach 1:
The patent uses input current as an intermediary measurement to indirectly determine output current. Instead of directly measuring output current through a sense resistor (which causes power loss), the system measures input current and uses the known multiplication/division factor N of the charge pump to calculate output current, thereby avoiding the power loss associated with direct output current measurement
Solution Approach 2:
The patent replaces the physical sense resistor measurement mechanism with a computational estimation approach. By substituting the direct electrical measurement (which requires physical intervention and causes power loss) with a mathematical calculation based on input current measurement and charge pump characteristics, the system eliminates the harmful power loss while maintaining measurement capability
2Measurement precision
If direct measurement of output current is implemented, then measurement accuracy is improved, but device complexity increases due to calibration challenges
Solution Approach 1:
The patent performs calibration actions in advance by characterizing the charge pump's multiplication/division factor N during manufacturing or initialization. This preliminary characterization allows the system to use a simple linear relationship (IOUT = IIN × N − Offset) for ongoing measurements, avoiding the need for complex real-time calibration procedures while maintaining measurement accuracy
Solution Approach 2:
The patent transforms the measurement problem by changing the measurement parameter from output current to input current. By measuring input current (which requires no calibration) and using the known parameter N (characterization factor), the system simplifies the measurement process while maintaining the ability to determine output current through the established relationship
Data Source
AI summary
The present disclosure relates to current sensing, and more particularly, to systems and methods for estimating the output current of a charge pump. In one embodiment, a method for estimating an output current of a charge pump is disclosed. The method comprises measuring, using a first sensing circuit, an input current into a switched capacitor power conversion circuit, and calculating, using a hardware processor, an estimated output current from the switched capacitor power conversion circuit as:IOUT=(IIN×N)−Offsetwherein IOUT is the estimated output current, IIN is the measured input current, N is a multiplication or division factor of the switched capacitor power conversion circuit, and Offset is an output current offset.