PSRR-Enhanced, Fast-Response Inverter-Based LDO for Mobile, IoT & HPC (28-nm CMOS)

Low-dropout (LDO) regulators are foundational to power integrity in mobile SoCs, IoT nodes, and HPC/AI accelerators. As processes push into sub-10 nm, architects need energy-efficient, compact, noise-resilient regulators with robust transient behavior.

🔍 Why LDO Design Is Critical in Modern Electronics

LDOs deliver clean, regulated rails close to the point-of-load, eliminating switching ripple where PSRR and fast transient response are paramount.

Where They Matter Most

• Mobile processors & battery devices: stable regulation improves efficiency and battery life in phones, wearables, tablets.
• AI accelerators & HPC: low-noise rails and sub-µs transients sustain performance in GPUs/NPUs and data-center silicon.
• 5G & automotive: base stations and ADAS rely on high-PSRR regulators that remain stable under extreme conditions.

📈 Key Contributions of the Proposed LDO Design

1) Inverter-Based Amplifier for Superior PSRR Core Idea

• Inverter-based loop sidesteps headroom limits common to classic error amplifiers.
• A non-inverting auxiliary amplifier (AUX) boosts PSRR, suppressing supply ripple that couples into the output.

2) Wide Voltage Operation for Mobile & IoT

• VIN: 0.4 V → 1.1 V
• VOUT: 0.2 V → 1.05 V
• Optimized for low-power processors and duty-cycled IoT systems.

3) Industry-Leading Fast Transient Response

4) Power Supply Rejection Ratio (PSRR)

• 44.3 dB @ 100 kHz, 25.0 dB @ 10 MHz (VIN = 1 V)
• > 30 dB PSRR up to 600 kHz (VIN = 0.6 V)

5) Compact Silicon Footprint for SoCs

• 28-nm CMOS, area 0.023 mm² — ideal for dense multi-rail integration.

🚀 Strengths & Industry Relevance

• Advanced Architecture: Inverter-based control with AUX enhancement raises the PSRR ceiling.
• Proven Behavior: Includes both simulation and measured benchmarks.
• Real-World Fit: Suited for battery-powered mobile, IoT, and automotive platforms where quiet rails are critical.

🔎 Areas for Further Research & Optimization

1) Sub-10-nm Scalability

Assess device noise, leakage, and matching as nodes migrate to 7 nm/5 nm; revisit compensation and biasing strategies.

2) Benchmark vs. Digital & Switched-Cap LDOs

Provide apples-to-apples comparisons on efficiency, response time, area, and noise under identical loads.

3) AUX Power Budget

Quantify the auxiliary amplifier’s quiescent and dynamic consumption to maximize end-to-end energy efficiency.

📝 Conclusion — Power Management IC Design

This work demonstrates a cutting-edge inverter-based LDO with excellent PSRR and nanosecond-class transients in 28-nm CMOS, making it a strong candidate for modern mobile and SoC platforms. Continued research into sub-10-nm behavior and system-level energy optimization will further unlock performance for next-gen electronics.

📌 Reference

Lee, J. Lim and J. Han, “A PSRR-Enhanced Fast-Response Inverter-Based LDO for Mobile Devices,” IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 71, no. 6, pp. 3226–3230, Jun. 2024. DOI: 10.1109/TCSII.2024.3357206.

Keywords: Low-Dropout Regulator (LDO), PSRR, fast-response LDO, CMOS PMIC, analog IC design, inverter-based LDO, mobile SoC power.

❓ FAQs

How does an inverter-based LDO improve PSRR?

By leveraging high transconductance per bias current and an AUX non-inverting stage that attenuates supply ripple, improving loop gain where PSRR matters.

Why target 0.4–1.1 V input range?

It aligns with deeply scaled cores and IoT rails, enabling efficient point-of-load regulation with minimal headroom.

What limits transient response in practice?

Output capacitance, pass-device gm, loop bandwidth, and compensation strategy; careful pole-zero placement and strong gm help achieve sub-100 ns settling.