Accurate on-chip current sensing technique for Buck converter

Abstract

Current mode bucks converters have many advantages over voltage mode control such automatic over-current protection, Better stability, better line regulation and faster dynamic response. Many different current sensing techniques have been developed and implemented sense the inductor current and use it a feedback loop to regulate the output voltage. Current sensing circuit needs to be highly accurate so as to have good line and load regulation minimum output voltage ripple. The proposed current sensing technique uses a cur mirror (Mp1 and Ma) to mirror the current of the transistor (Mp1) to Ma (with a w ratio of 10000:1, so that carried by Ma, and hence its power dissipation. Is small). Sensed current is converted to voltage using a resistor. Which is used in the feedback loo1 control the width of the pulses? The accuracy of the proposed circuit is98% which gives regulation of 0.8386% and load regulation of 0.3115%. The output voltage ripple of the cur is 10mV.