Power Delivery Networks for Embedded Mobile SoCs: Architectural Advancements and Design Challenges

Muhammad Abrar Akram, In Chul Hwang, Sohmyung Ha

Research output: Contribution to journalArticlepeer-review

Abstract

Conventional power delivery networks (PDNs) and power management techniques using off-chip power converters with bulky passive components cannot meet the ever-evolving power delivery requirements of high-performance modern system-on-chips (SoCs). In SoCs, heterogeneous components, including multi-core processors and mixed-signals peripheral circuits, require state-of-the-art PDNs to provide high-quality power-on-demand with minimum latency, simultaneously achieving the small-factor, high conversion efficiency, and minimum current consumption. To satisfy these power delivery requirements, various PDNs have been developed over the past decades, such as the conventional architectures using off-chip power converters, architectures using in-package power converters and fully-integrated power converters, and heterogeneous architectures (off-chip power converters and on-chip regulators). This paper reviews these architectural advancements of the PDNs and their advantages and limitations, which leads us to discuss a heterogeneous PDN structure consisting of a highly efficient off-chip switching-mode power converter and multiple highly precise small linear regulators integrated on chip at point-of-load locations. The heterogeneous PDN has been proved one of the most suitable architectures to achieve high-quality fine-grained on-chip power delivery and management in SoCs. This paper also discusses unified voltage and frequency regulators (UVFRs), which support dynamic-variation-aware dynamic voltage and frequency scaling (DVFS) for fine-grained power management in multi-core processors. Based on the UVFR, we propose a modified heterogeneous PDN using frequency-referenced digital low-dropout regulators (FR-DLDOs) for more efficient DVFS, eliminating the need for band-gap circuits to provide reference voltages. As an exemplary implementation of FR-DLDO for this PDN, we present an FR-DLDO with a transient-boost control, which accelerates the transient response. The transient-boost control is activated dynamically only when an abrupt change happens out of the steady state. The implemented FR-DLDO fabricated in a 40-nm CMOS process outperforms other FR-DLDOs in the figure-of-merit and peak power efficiency while driving 40 mA of load current.

Original languageEnglish (US)
Article number9382257
Pages (from-to)46573-46588
Number of pages16
JournalIEEE Access
Volume9
DOIs
StatePublished - 2021

Keywords

  • Power delivery network (PDN)
  • digital LDO
  • dynamic-voltage and frequency scaling (DVFS)
  • dynamic-voltage scaling (DVS)
  • fine-grained power management
  • frequency-referenced digital LDO (FR-DLDO)
  • low-dropout regulator (LDO)
  • transient-boost control
  • unified-voltage and frequency regulator (UVFR)

ASJC Scopus subject areas

  • Computer Science(all)
  • Materials Science(all)
  • Engineering(all)

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