A Time-Division-Multiplexed Clocked-Analog Low-Dropout Regulator

Abstract

This paper presents a time-division-multiplexed (TDM) clocked-analog low-dropout regulator (CLDO) that shares one controller between multiple output channels. Clocked-analog operation is introduced to create idle periods that enable the shared controller to independently regulate different output channels through time-division multiplexing. Furthermore, an asynchronous transient enhancing technique is presented. Thanks to the controller sharing, the TDM CLDO is more area-efficient than conventional designs for supplying multiple outputs, especially when power stages and on-chip loads are small. To verify the effectiveness of the TDM CLDO, a dual-channel version is fabricated in a 130 nm CMOS process. Measurement results show that it can independently track two 100 kHz 0.3 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> sinusoidal signals with 4 mV average output error at 100 Ω load and 6 MHz clock frequency. For load transient responses, it can independently regulate two output channels to 1.05 V and 0.95 V with 41 mV/88 mV and 67 mV/39 mV overshoot/undershoot when both channels experience 5 mA current steps at 1.2 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dd</sub> . To the best of our knowledge, this is the first time that hardware sharing is implemented for continuous closed-loop systems.