A Fast-Transient Capacitorless LDO With Dual Paths Active-Frequency Compensation Scheme

Abstract

This article presents an area-efficient and fast-transient capless low-dropout regulator (LDO) with satisfactory static and dynamic performance in the full load current range. Active-capacitor frequency compensation strategy with push–pull charging ability is employed to reduce on-chip compensation cap without degrading loop stability at light load and improve transient response speed simultaneously. Moreover, in order to drive this compensation capacitance, it makes use of an adaptively biased signal- and transient-current boosting error amplifier as well as transient enhancement circuit with nonlinear control to achieve high loop gain/bandwidth and slew rate. The proposed LDO is implemented in a 0.35-μm 5V-CMOS process and occupies an active chip area of 0.077 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Experimental results demonstrate that it can deliver 100-mA load current at 200-mV dropout voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</sub> = 2.7–3.3 V, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">load</sub> ≤100 pF). It consumes 66- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> A quiescent current at light load and can recover within 0.7 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s for load transient. The voltage spikes at the output, undergoing a maximum load current change, are controlled well below 260 mV and good line/load regulation is achieved synchronously.

Topics & Concepts