University of South Florida

University of Minnesota

Longfei Wang

Ulya R Karpuzcu

Selçuk Köse

S Karen Khatamifard

A DLDO has a configuration that mitigates performance degradation associated with limit cycle oscillation (LCO). The DLDO comprises a clocked comparator, an array of power transistors, a digital controller and a clock pulsewidth reduction circuit. The digital controller comprises control logic configured to generate control signals that cause the power transistors to be turned ON or OFF in accordance with a preselected activation/deactivation control scheme. The clock pulsewidth reduction circuit receives an input clock signal having a first pulsewidth and generates the DLDO clock signal having the preselected pulsewidth that is narrower that the first pulsewidth, which is then delivered to the clock terminals of the clocked comparator and the digital controller. The narrower pulsewidth of the DLDO clock reduces the LCO mode to mitigate performance degradation caused by LCO.

Method and apparatus for mitigating performance degradation in digital low-dropout voltage regulators (DLDOs) caused by limit cycle oscillation (LCO) and other factors

An apparatus and method are provided for mitigating performance degradation in digital low-dropout voltage regulators (DLDOs) caused by the effects of aging on the power transistors of the DLDO, such as by the effects of negative bias temperature instability (NBTI)-induced aging, for example. The apparatus comprises a shift register for use in a DLDO that is configured to activate and deactivate power transistors of the DLDO to evenly distribute electrical stress among the transistors in a way that mitigates performance degradation of the DLDO under various load current conditions. In addition, the shift register and methodology can be implemented in such a way that nearly no extra power and area overhead are consumed.

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Longfei Wang