Synchronization and control of high frequency dc-dc converters .

摘要

Modern high performance microprocessor systems in advanced CMOS technologies demand high peak current, large current transients, stringent voltage tolerance and high power dissipation. In order to cope with these requirements, near-load power delivery solutions are proposed to integrate the voltage regulator module near or within the processor die for localized power delivery. This solution is based on high frequency dc-dc converter designs, leading to fast load response, reduction in the component sizes and reduction in the external peak current. The objective of this work is to explore several high frequency dc-dc converter designs and synchronization techniques for near-load power delivery systems.This work begins with an overview of high frequency power converter design techniques. The multiphase hysteretic controlled converter is investigated in detail as it provides current staggered operation for ripple reduction and fast load response. We present a novel delay locked loop based hysteretic control scheme for high-frequency multiphase buck converters topologies to enable synchronous and stable operation. The converter employs the switching signal from the main voltage-regulation control loop and generates multiphase control signals with accurate duty cycle adjustment. Its key advantages include large output voltage range determined by the attainable duty cycle of the DLL.A digital phase locked loop frequency locking technique for high frequency hysteretic controlled dc-dc buck converters is also presented. The proposed technique achieves constant operating frequency over a wide output voltage range, eliminating the dependence of switching frequency on duty cycle or output voltage conversion range. The DPLL is programmable over a wide range of parameters and can be locked to a reference clock to ensure the converter switching frequency falls outside power supply resonance bands.Finally, this thesis reports a digital delay locked loop to synchronize a high frequency multiphase boost converter. The boost converter employs current mode pulse-width-modulation, and the D-DLL provides multiphase synchronization signals with accurate duty cycle control. The proposed digital control scheme can easily accommodate high frequency dc-dc converters with different structures and control loops, enabling fast and flexible design strategies for power management systems. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)