What is EMI?
Electromagnetic Interference (EMI) refers to unwanted electromagnetic signals that disturb the normal operation of electronic circuits.
EMI and EMC issues commonly arise in high-speed digital systems, power electronics, RF circuits, and embedded systems.
EMI can originate from:
- Switching power supplies
- Motors and relays
- High-frequency clocks
- Wireless communication devices
If not controlled, EMI can lead to system failures and regulatory non-compliance.
Types of EMI
Understanding the types of EMI is essential for effective EMI and EMC design.
1. Conducted EMI
Conducted EMI travels through physical conductors such as power lines, signal cables, and PCB traces.
Conducted emissions testing is a key part of EMI and EMC testing.
2. Radiated EMI
Radiated EMI spreads through air as electromagnetic waves and affects nearby circuits.
Radiated emissions are critical in EMI and EMC compliance.
3. Narrowband EMI
Narrowband EMI is generated by oscillators, RF transmitters, and clock circuits.
4. Broadband EMI
Broadband EMI is caused by motors, switching regulators, and fast digital transitions.
Effects of EMI
Poor EMI and EMC design can cause:
- Data corruption in communication systems
- Malfunction of medical equipment
- Poor wireless signal quality
- Audio and video noise
- Product failure during EMI testing
This is why EMI and EMC standards are mandatory for most electronic products.
What is EMC?
Electromagnetic Compatibility (EMC) refers to the ability of a device to operate correctly in its electromagnetic environment
without causing or suffering from EMI.
In simple terms, EMC ensures EMI is controlled.
EMI and EMC always go hand in hand—EMI is the problem, and EMC is the solution.
Two Key Aspects of EMC
1. EMI Emissions
The device should not emit excessive electromagnetic noise beyond allowed limits defined in EMI and EMC standards.
2. EMI Immunity
The device should continue to function properly even when exposed to external electromagnetic interference.
Key Differences Between EMI and EMC
| Aspect | EMI | EMC |
|---|
| Definition | Unwanted electromagnetic interference | Ability to work without interference |
| Focus | Noise generation | System tolerance |
| Testing | How much noise is emitted | Emission & immunity compliance |
| Goal | Identify interference | Ensure reliable operation |
Understanding the difference between EMI and EMC is a fundamental concept taught in professional embedded training programs.
EMI and EMC Standards
Common EMI and EMC standards include:
- FCC (USA)
- CISPR
- IEC standards
- Automotive EMC standards (ISO, CISPR 25)
Compliance with EMI and EMC standards for automotive and industrial products is mandatory before market release.
How to Reduce EMI and Achieve EMC Compliance
1. Proper PCB Design
- Use solid ground planes
- Minimize loop areas
- Separate noisy and sensitive circuits
- Follow EMI and EMC PCB guidelines
2. Filtering and Decoupling
EMC shielding materials and filters play a major role in EMI suppression.
3. Shielding
- Metal enclosures
- Shielded cables
- EMC shielding materials for high-frequency circuits
4. Compliance Testing
- Conducted emissions test
- Radiated emissions test
- Immunity testing
- EMI pre-compliance testing before final certification
EMI and EMC in Embedded Systems
In embedded electronics, EMI and EMC issues often arise due to:
- High-speed microcontrollers
- Switching regulators
- Long PCB traces
Professionals trained at IIES (Indian Institute of Embedded Systems)
gain strong practical exposure to EMI and EMC testing, PCB layout best practices, and real-world debugging techniques—making IIES one of the
best embedded courses in Bangalore.
Why EMI and EMC Knowledge Is Critical for Engineers
Mastering EMI and EMC:
- Improves product reliability
- Reduces certification failures
- Saves redesign cost
- Enhances career opportunities in automotive and embedded domains
This is why EMI and EMC basics are a core part of advanced embedded systems training.
