A Wide-Input 0.25 um BCD LDO with Dual-Stage Amplifier and Active Ripple Cancellation for High PSRR and Fast Transient Response

TL;DR

This paper introduces a wide-input BCD LDO with dual-stage amplification and active ripple cancellation, achieving high PSRR and fast transient response suitable for high-performance SoCs and portable electronics.

Contribution

It presents a novel wide-input LDO architecture with active ripple cancellation and adaptive fast feedback, improving PSRR and transient response simultaneously.

Findings

Achieves -75 dB low-frequency PSRR

Maintains output droop under 0.65 V during load steps

Reaches recovery within 16 microseconds

Abstract

Demand for on-chip low-dropout regulators (LDOs) with both high power-supply rejection ratio (PSRR) and fast transient response is growing as system-on-chip (SoC) integration increases. However, conventional LDO architectures face difficulty achieving these performance metrics simultaneously over wide input voltage ranges. This paper presents a wide-input linear regulator implemented in 0.25 um BCD technology that attains high PSRR and swift load-transient performance while maintaining low quiescent current. The proposed LDO employs a dual-stage error amplifier architecture and active ripple cancellation along both the power path and the error amplifier's supply to significantly enhance PSRR across frequency. An adaptive fast feedback branch together with an on-chip frequency compensation network is introduced to accelerate transient response without compromising stability. A two-stage PSRR analytical model and a three-frequency-band PSRR interpretation framework are developed to guide the design. Cadence Spectre simulations of the 14 V-output LDO demonstrate a -75 dB low-frequency PSRR, and during a 50 uA - 4 mA load step the output voltage droop is kept under 0.65 V with recovery within 16 us. These results validate the effectiveness of the proposed architecture and analysis, indicating that the design meets the stringent requirements of analog/RF SoCs and portable electronics.