Ramnarayanan Muthukaruppan

Digitally controlled voltage regulator using oscillator-based ADC with fast-transient-response and wide dropout range in 14nm CMOS

In this paper, we propose a digitally controlled voltage regulator with fast-transient-response using an oscillator based ADC implemented in 14nm CMOS technology. The transient response is critical to mitigate droop for large di/dt seen in cores and wide dropout range helps enable DVFS to improve power/performance ratio. In this work, we target 1-1.15V input voltage with output voltage range of 0.5–1.12 V with minimum 30mV dropout, and load current range of >22× with 0.1A–2.2A at 50mV dropout with <0.006mV/mA load regulation using 10-bit power-stage binary control and characterized using a slew-rate programmable synthetic resistive load on-die to mimic core with 18nF load capacitance implemented on-die using area over load.

A digitally controlled linear regulator for per-core wide-range DVFS of atom™ cores in 14nm tri-gate CMOS featuring non-linear control, adaptive gain and code roaming

A digitally controlled LDO in 14nm tri-gate CMOS powering an Atom™ core with embedded power gates enables per-core DVFS over a wide voltage-frequency range. The LDO demonstrates 99.6% peak current efficiency at 2.5A load current and provides a power density of 26.1 W/mm2. The multi-mode digital controller featuring non-linear mode and adaptive gain achieves <20ns settling time with a 100mV droop for a 1.2A load step. A code roaming algorithm complements the feedback controller to successfully mitigate reliability issues from power gate transistor self-heating and electromigration.