DC Power Supply Design in Portable Systems

Design of microfabricated inductors for microprocessor power delivery

“…1). If we assume that advanced packaging and interconnect designs have minimized stray inductance such that one lumped capacitor represents bypass capacitance and converter output capacitance, and assume that advanced control operates the power switches in the ideal manner to optimize transient behavior, the smallest possible dip in output voltage due to a loadcurrent step of ¡Á may be calculated as ¡Î ´¡Áµ ¾ Ä ¾ ´Î Ò Î ÓÙØ µ (1) where ¡Á is the size of the current step, Ä is the inductor value, is the total bypass and output capacitance, and Î Ò and Î ÓÙØ are the input and output voltages respectively. This shows that minimizing the inductor value is a key strategy for improving performance; however, reducing the inductor value leads to increased current ripple and higher losses.…”

“…The resulting inductor requirement is for low loss with high ripple current and high frequency. One attractive choice for ripple current level in the inductor is to allow enough ripple to effect zero voltage switching [1].…”

“…This current must be supplied efficiently at voltages between 1 and 1.5 V, and the voltage must remain stable despite rapid changes in load current. Circuit and control innovations [1], [2], [3], [4], [5], [6], [7], [8] have been developed to improve performance in this application. As discussed in Section II, the inductor is associated with fundamental performance constraints in a buck-converter for this application, and thus is crucial to high-performance power delivery.…”

Converter and inductor design for fast-response microprocessor power delivery

“…The magnitude of the ripple current in the This work was supported in part by the Intel Mobile Research Council and by the National Science Foundation under grant ECS-9875204. ÝNow with Intel Corp., DuPont WA ÞNow with Lutron Electronics, Coopersburg PA inductor can be described by the ripple ratio (Ö Ê ); Ö Ê Á ÔÔ Á ÓÙØ (1) where Á ÔÔ is peak-to-peak ac ripple current, and Á ÓÙØ is the output current of the converter. An increasing or decreasing load current step will result in an output voltage dip or rise, respectively.…”

“…This current must be supplied efficiently at voltages near 1 V, and the voltage must remain stable despite rapid changes in load current. Circuit and control innovations [1], [2], [3] have been developed to improve performance in this application. In this paper, we assume ideal control of a buck converter, and analyze the capability of the circuit to respond to a rapid load current step.…”