A Capacitorless Flipped-Voltage-Follower-Based Low-Dropout Regulator Incorporating Adaptive-Compensation Buffer

This brief presents an output-capacitorless low-dropout (OCL-LDO) regulator based on flipped-voltage-follower (FVF) and dual pMOS pass transistors. An adaptive-compensation buffer (ACB) dynamically regulates the operation of the pass transistors. Specifically, when the load current falls below 5 mA, only the smaller pass transistor is activated; otherwise, both pass transistors are engaged, thereby simultaneously mitigating the minimum load current requirement for FVF architecture and extending the load current ranging from 0 to 30 mA while maintaining stability without an external load capacitor. At 1.15-V supply voltage and 0-mA load current, the quiescent current is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6~\mu $ </tex-math></inline-formula>A. The output voltage is 1.0 V with a dropout voltage of 0.15 V. Measurements show that with a load current stepping from 0 to 30 mA at an edge time of 100 ns, the output voltage undershoot is 0.2 V with a recovery time of 200 ns while achieving a load regulation of 0.23 mV/V. Our OCL-LDO is fabricated in a 180-nm CMOS with an active area of 0.031 mm2.