DC–DC Buck Converter Using Analog Coarse-Fine Self-Tracking Zero-Current Detection Scheme

Abstract

This brief proposes a dc–dc buck converter using an analog coarse-fine self-tracking zero-current detection (AST-ZCD) scheme. The AST-ZCD detects the zero-current by measuring the voltage level across a freewheeling transistor. It adjusts the nMOS turn-off time using an amplifier, capacitors, and current sources instead of large numbers of shift register bits and unit delay cells in the conventional digital self-tracking zero-current detection (DST-ZCD). It also reduces the zero-current self-tracking time by using coarse-fine current-sources when the output current transition is large. The proposed dc–dc buck converter was fabricated with a 0.18- $\boldsymbol {\mu }\text{m}$ CMOS process. The AST-ZCD reduces the area by 94%, the power consumption by 80%, and the zero-current self-tracking time by 82% compared to the DST-ZCD.