System and method for controlling electromagnetic interference in portable electronic devices having a radio frequency subsystem

A portable electronic device comprising:

• a radio frequency (RF) communication subsystem configured to generate a RF activity status signal indicative of a RF activity status of the RF communication subsystem;
• and
• a switch-mode power supply subsystem configured to receive the RF activity status signal, the switch-mode power supply subsystem operable to output an output electrical signal as a function of the RF activity status signal, the output electrical signal being a first output electrical signal when the RF activity status signal indicates inactivity of the RF communication subsystem, the output electrical signal being a second output electrical signal when the RF activity status signal indicates activity of the RF communication subsystem, the first output electrical signal being a pulse-width modulated signal having an initial slew rate, the second output electrical signal being a modified pulse-width modulated signal having a modified slew rate, the modified slew rate being less than the initial slew rate, the portable electronic device producing an electromagnetic interference (EMI) signal as a function of the output electrical signal, the EMI signal being lower for the second output electrical signal than for the first output electrical signal.