EMI and EMC Compliance in Smart Phone

EMC within electronic components has become an increasingly important issue for embedded designers to contend with. As system frequencies and the need for lower supply voltages increase, the end application becomes more and more vulnerable to the negative affects of EMI. These electrical influences can be generated by either radiated or conductive EMI sources. Radiated sources include anything electrical or electromechanical, including motors, power lines, antennas, traces on a PCB (Printed Circuit Board), and even the silicon components on the PCB. Conductive EMI primarily shows itself as electrical “noise” on the power supply lines of an application and can be caused by induced voltage spikes from other devices within a system.

  • Electromagnetic Interference (EMI): Electromagnetic emissions from a device or system that  interfere with the normal operation of another device or system. EMI is also referred to as Radio Frequency Interference (RFI)
  • Electromagnetic Compatibility (EMC): The ability of equipment or system to function satisfactorily in its Electromagnetic Environment (EME) without introducing intolerable electromagnetic disturbance to anything in that environment

For an EMIC problem to exist:

  • System/Device that generates interference
  • System/Device that is susceptible to the interference
  • Coupling path: The coupling path may involve one or more of the following coupling mechanisms:

emc5

  1. Conduction – electric current, power line
  2. Radiation – electromagnetic field
  3. Capacitive Coupling – electric field
  4. Inductive Coupling – magnetic field

Mitigation of EMIC Issues:

  • Reduce interference levels generated by culprit
  • Increase the susceptibility threshold of the victim-Reduce the effectiveness of the coupling path
Source (Culprit) Coupling Path Receiver (Victim)
Modify signal routing Increase Separation Modify signal routing
Add local filtering Shielding Add local filtering
Operating freq selection Reduce # Interconnects Operating Freq selection
Freq Dithering Filter Interconnections
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