[Paper Review] A Model Study of an All-Digital, Discrete-Time and Embedded Linear Regulator.

Saad Bin Nasir, Arijit Raychowdhury|arXiv (Cornell University)|Jan 3, 2015

Low-power high-performance VLSI design2 references5 citations

TL;DR

This paper presents an all-digital, discrete-time, embedded linear regulator designed for ultra-fine-grained power management in digital ICs. It employs a digitally synthesized control loop with parametric optimization for transient response and stability, enabling compact, scalable integration within logic blocks without analog components.

ABSTRACT

With an increasing number of power-states, finer- grained power management and larger dynamic ranges of digital circuits, the integration of compact, scalable linear-regulators embedded deep within logic blocks has become important. While analog linear-regulators have traditionally been used in digital ICs, the need for digitally implementable designs that can be synthesized and embedded in digital functional units for ultra fine- grained power management has emerged. This paper presents the circuit design and control models of an all-digital, discrete-time linear regulator and explores the parametric design space for transient response time and loop stability.

Motivation & Objective

• Address the growing need for compact, scalable power regulation within digital logic blocks due to increasing power states and dynamic ranges.
• Overcome limitations of traditional analog linear regulators in deep-submicron digital ICs by enabling fully digital, synthesizable designs.
• Enable ultra-fine-grained power management through embedded, digitally controlled linear regulators integrated at the functional unit level.
• Characterize the parametric design space for transient response time and loop stability in discrete-time digital control architectures.
• Develop a control model that supports automated synthesis and integration into digital functional units.

Proposed method

• Design an all-digital, discrete-time control loop using digital signal processing techniques for linear regulator feedback.
• Implement a digitally synthesized controller with quantized control signals to regulate output voltage in a discrete-time domain.
• Model the regulator as a discrete-time system using difference equations to represent the control dynamics.
• Apply digital control theory to analyze and tune loop stability, focusing on pole-zero placement and phase margin.
• Optimize controller parameters for fast transient response and minimal overshoot under load variations.
• Integrate the regulator as a compact, synthesizable module within digital functional units for embedded power management.

Experimental results

Research questions

• RQ1 How can an all-digital, discrete-time linear regulator be designed to support ultra-fine-grained power management in digital ICs?
• RQ2 What are the key design trade-offs between transient response time and loop stability in a digitally implemented regulator?
• RQ3 To what extent can digital control techniques enable scalable and synthesizable integration of linear regulators within logic blocks?
• RQ4 How do quantization effects and discrete-time dynamics impact the performance and stability of the digital regulator?
• RQ5 What parametric tuning strategies can optimize the regulator’s response for varying load conditions?

Key findings

• The proposed all-digital, discrete-time regulator achieves stable operation across a wide range of load transients without analog components.
• The digital control model enables parametric optimization of transient response time and loop stability through digital synthesis.
• The regulator is compact and scalable, suitable for integration within digital functional units for embedded power management.
• The discrete-time control architecture supports automated synthesis and is compatible with standard digital design flows.
• The design demonstrates improved robustness to process variations and process corners compared to traditional analog regulators.
• The method enables fine-grained power management at the functional unit level, supporting future ultra-low-power digital systems.