A Delay-Locked Loop Synchronization Scheme for High-Frequency Multiphase Hysteretic DC-DC Converters
Li, P.
Xue, L.
Hazucha, P.
Karnik, T.
Bashirullah, R.
This paper appears in: Solid-State Circuits, IEEE Journal of
Publication Date: Nov. 2009
Volume: 44,
Issue: 11
On page(s): 3131-3145
ISSN: 0018-9200
Digital Object Identifier: 10.1109/JSSC.2009.2033508
Current Version Published: 2009-11-03
Abstract This paper reports a delay-locked loop (DLL) based hysteretic controller for high-frequency multiphase dc-dc buck converters. The DLL control loop employs the switching frequency of a hysteretic comparator as reference to automatically synchronize the remaining phases and eliminate the need for external synchronization. A dedicated duty cycle control loop is used to enable current sharing and ripple cancellation. We demonstrate a four-phase high-frequency buck converter that operates at 25–70 MHz with fast hysteretic control and output conversion range of 17.5%–80%. The converter achieves an efficiency of 83% at 2 W and 80% at 3.3 W. The circuit has been implemented in standard 0.5 $mu{hbox {m}}$ 5 V CMOS process.
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