Inductor design for PWM buck converter operated as dynamic supply or amplitude modulator for RF transmitters

Pulse-width modulated (PWM) DC-DC buck converters can play a critical role in high-efficiency power management systems when operated as dynamic power supplies or amplitude modulators. However, no analysis or design methodology currently exists for a buck converter used as variable-output supply in continuous conduction mode (CCM). This paper describes a key difference in analysis and design for this application, namely the method for determining the optimum inductance value. New inductor design equations, different from those derived for fixed-output CCM buck converters in the existing literature, are presented and verified through simulation of an example design.