Summary of Electro Magnetic Interference

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  • Electromagnetic interference ( EMI) is an interference to an electronic device by electrical energy generated nearby.
  • The effect of EMI is becoming more and more important now. a days due to the vast advancement in the field of electronics and mobile phone industry.
  • There are mainly three general classes of EMI problems. – Conducted EMI, Radiated EMI and Electrostatic discharge.
  • Conduction EMI requires a wire or other conductor to transfer the EMI from one place to another.
  • Radiated EMI does not require any wire to carry interference and it is transmitted or radiated through space.
  • ESD is the buildup of electrostatic potentials on tools, objects and the human body caused by any mechanical action.
  • EMI varies with grounding methods, types of shielding etc.
  • EMI effect to the biomedical sensor can be very serious because the EMI can superimpose on the bioelectric signals and can cause measurement errors.
  • There are three main transmission paths for EMI into a sensor system called conduction, penetration and leakage.
  • Conduction EMI occurs when a signal induces current into the exposed cable.
  • In penetration EMI the Electromagnetic wave cuts across the sensor and due to this RF currents are produced in the sensor circuitry.
  • Even though we use shields, the EMI will enter the sensor circuit through breaks in the shielding. It is the effect of leakage EMI.
  • A solution for EMI in sensor circuits is filtering and another solution is shielding.
  • Filtering is used to attenuate the RF signal before they penetrate the sensor circuits.
  • Shielding involves the covering of source or receiver (or both) by metallic shields consists of copper, aluminum or galvanized steel.
  • Shielding is of two types called source shielding and receiver shielding.
  • Double shielding is same as single shielding except the fact that hoe two shields are used.
  • The main types of signal overload problems are Desensitization, Generation of unwanted harmonics, Inter-modulation frequencies and Distortion of desired signal.

Author Bio: The Author of this article, Sreejith is writing articles onUltrasound Scan Modes and Electronics and Communications

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