A Compact and Accurate Self-Subtracted R LG Current Sensor for Low-Voltage Monolithic Multiphase Buck Converter
Journal
IEEE Transactions on Power Electronics
Journal Volume
40
Journal Issue
2
Start Page
3251
End Page
3261
ISSN
0885-8993
1941-0107
Date Issued
2025-02
Author(s)
Abstract
This article introduces a novel self-subtracted RLG current sensor (SSRLGCS) for a low-voltage monolithic multiphase buck converter. The sensor subtracts the product of the duty cycle and VIN voltage from VLX voltage with a simple RC filter to obtain the inductor current information with a sensing gain equal to RLG. By adjusting the RC filter corner frequency, this sensor effectively extracts either the full waveform or dc information of the inductor current, facilitating modulation or phase current balancing, respectively. Furthermore, precisely matching the upper and lower power switch on-resistances, which is easily and is the only design overhead of SSRLGCS, achieved in monolithic power integrated circuit design, ensures accurate inductor current extraction. The developed sensor serves as an on-chip solution for balancing a multiphase buck converter without a traditional off-chip bulky matching filter associated with direct-current resistance current sensing. It guarantees the current balance accuracy independent of off-chip parasites, inductor mismatch, and temperature coefficient. A dual-phase buck converter integrated circuit was fabricated using a taiwan semiconductor (TSMC) 0.18 μm complementary metal-oxide-semiconductor (CMOS) process, occupying a compact 0.586 mm² whole chip area (including the power stage) and 0.062 mm² current sensor and current balance circuit area for verifying the SSRLGCS dedicated to the current balance. The measured current balance error is within 2.2% of a loading ranging from 1 A to 2 A. A 71% current sharing accuracy improvement between the two phases is achieved. Moreover, the standalone SSRLGCS measured sensing error falls within 50 mA with a loading range of 1.2 A to 2.6 A.
SDGs
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Type
journal article