Small Signal Modeling of a High Bandwidth Voltage Regulator Using Coupled Inductors

Today's voltage regulator (VR) for the microprocessor requires a current loop to achieve adaptive voltage positioning and phase current sharing. A fundamental limitation, current loop sample hold effect, limits the control bandwidth to be pushed beyond 1/6 of the switching frequency. This paper...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2007-03, Vol.22 (2), p.399-406
Main Authors: Ming Xu, Jinghai Zhou, Kaiwei Yao, Lee, F.C.
Format: Article
Language:English
Subjects:
Applied sciences
Bandwidth
Bandwidths
Buck converters
Capacitors
Circuit properties
Circuits
Controllers
Coupled inductors
Current control
Electric currents
Electric, optical and optoelectronic circuits
Electrical engineering. Electrical power engineering
Electronic circuits
Electronics
Exact sciences and technology
high bandwidth
Inductors
Integrated circuits
Integrated circuits by function (including memories and processors)
Joining
Magnetic devices
Microprocessors
Regulators
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Signal convertors
small signal modeling
Switching
Switching frequency
Transformers and inductors
Virtual reality
Voltage
Voltage regulators
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Summary:Today's voltage regulator (VR) for the microprocessor requires a current loop to achieve adaptive voltage positioning and phase current sharing. A fundamental limitation, current loop sample hold effect, limits the control bandwidth to be pushed beyond 1/6 of the switching frequency. This paper reveals the limitation of the control bandwidth of a two-phase buck converter using peak current control scheme. The limitation can be overcome by coupling the two output inductors. A new small signal model is proposed to study the sample hold effect in coupled-inductor implementations. The relationship between the coupling coefficient and the sample hold effect is then discussed. Based on these understandings, a strongly coupled two-phase buck converter has double the bandwidth of the noncoupled VR; and this is experimentally verified
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2006.889905