SYSTEM AND METHOD FOR CONTROLLING ELECROMAGNETIC INTERFERENCE IN PORTABLE ELECTRONIC DEVICES HAVING A RADIO FREQUENCY SUBSYSTEM

摘要

A portable electronic device that has a radio frequency communication subsystem operationally connected switch-mode power supply subsystem. The switch-mode power supply subsystem generates a pulse-width modulation electrical signal that produces electromagnetic interference. The switch-mode power supply subsystem can reduce the slew rate of the pulse-width modulation electrical signal when the radio-frequency communication subsystem is active. This reduces the level of the electromagnetic interference signal only during radio frequency communication, which improves the efficiency of the radio frequency communication. Not having the reduced slew rate when there is no radio frequency communication allows for higher modulation efficiency.