A High-Accuracy Current Sensing Circuit with Clamping Current Compensation for Current-Mode DC-DC Buck Converter

In this paper, a detailed analysis method of eliminating clamping current error is first proposed. A high accuracy on chip current sensing circuit with clamping current compensation technique for current-mode DC-DC buck converter is presented. When the aspect ratios of the switch transistor and the sensing transistor meet certain proportion, the clamping current error can be eliminated. At the same time, the current sensing circuit has no operation amplifier so that it wouldn’t reduce the power efficiency. The simulated results show that the accuracy of proposed current censing circuit is higher than 94% and up to 99.7% for load current from 50mA to 500mA.

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