1. Origin of Emission and Susceptibility in ICs

2. Printed circuit boards
EMC Introduction
Two main concepts:
Susceptibility to EM waves
Emission of EM waves
Components
Printed circuit boards
Equipments
System
Noise
Personnal entrainments
Safety systems
interferences
Susceptibility to radio frequency interference is illustrate in the case of a very high radar wave illuminating an airplane. This situation is very common at the proximity of airports. A Giga-watt pulse is received by the the plane, which captures some energy which may flow to the equipment, the board and finally to the component.
On the other hand, the parasitic emission due to the integrated circuit inside a car may jeopardize the correct behavior of personal devices such as mobile phones, and RF links. In some case, the parasitic energy may be high enough to parasite the safety systems of the car.
Hardware fault
Software failure
Function Loss

3. Source of Electromagnetic Interferences
Natural disturbances (cosmic rays, thunder)
Radio communications, wireless, radars,… IC
Electrical Overstress IC
Inductive loads, motors

4. Origin of Parasitic Emission
Basic mechanisms for core current: CMOS inverter exemple
VDD
Switching current
IDD
(0.1mA)
IDD
(0.1mA)
ISS
(0.1mA)
Vin
Voltage
Time
Output capa
VOUT
VSS
ISS (0.1mA)
Time
One of the major source of perturbation is the current flowing inside each elementary gate of the integrated circuit. Let us consider the CMOS inverter, supplied by a high voltage VDD (2V in 0.18µm) and ground VSS (0V). When the input falls to 0 (i.e logic level “0”), a current (around 0.5mA) charges the capacitance through the pull up device.
When the input rises to 2V, that is a logic level “1”, a similar current flows through the pull down device and discharges the capacitance.

5. Origin of Parasitic Emission
The increasing speed and the high level of integration generate a stronger noise:
50ps
i(t)
Time
Vdd
Vdd
i(t)
Vss
Vss
Internal switching noise
Switching gates
Simultaneous Switching Noise
Main noise sources comes from AC current sources:
Clock-driven blocks, synchronized logic
Memory read/write/refresh
I/O switching

6. Increase parasitic noise
Origin of Parasitic Emission
Why technology scale down makes things worse ?
Time
New process
Volt
Old process
Current level keeps almost constant but:
Faster current switching
Stronger di/dt
Increase parasitic noise
Current
di/dt
Old process
Reduc Voltage swing => less E field
With the technology scale down, the supply voltage is reduced and the signals switch faster within interconnects (From voltage to scaled voltage). In 0.18µm technology, the switching is about 100ps (Pico-second or second), with a 2V swing. Concerning currents, the amplitude of elementary peaks appearing on supply lines of each elementary gates are sharper, but their amplitude remains constant (0.5mA in 100ps, per gate). Consequently, stronger di/dt are observed, leading to increased emission problems.
New process
Time

7. Origin of Parasitic Emission
Example: evaluation of switching current in an IC
0.1 mA / Gate in 100ps
1 Billion gates (32 Bit Micro) => 100A
10% switching activity => 10A
10% spreading of current peak (non synchronous switching) => 1A in 1ns
0.1 mA
Ampere
0.1 ns
time
Vdd
Vss
i(t)
Current / gate
Ampere
1 ns
time
Current / Ic
1 A
0.1 ma/gate in 100 ps, 10 million (base band), 10 K(8bits), 100K (16 bits), 1M (32 bits). % switching activity = 10 %, /10 because spread current = 1 A peak sur 1 ns. 16 bits : 100 mA sur 1 ns, 32 bits = 1A 500 ps…

8. Origin of Parasitic Emission
Example: evaluation of SSN
L=0.6nH/mm
L=1nH/mm
VDD
Lead = 10 mm
Evaluate SSN amplitude
1 A en 1 ns
Puce
Lead = 10 mm
VSS

9. Susceptibility issues
Power supply decrease & Noise margin reduction :
=> Increase of ICs sensibility to parasitic noise
Supply (V)
5.0
3.3
2.5
I/O
1.8
1.2
Tension cœur: réduire la puissance consommée, fragilité des oxyde
Tension I/O: reduction => aller + vite de 0 à VDD, mais – rapide pour des raison de compatibilité entre techno
0.8
Core
0.5µm
0.35µm
0.18µm
90nm
65nm
45nm
Technology

10. Susceptibility Issues
1-10GHz : Packages act as very good antennas
Antenna optimal size:
EMC of ICs
issues
La longueur d’onde est de 10cm a 3GHz et l’antenne optimale a une taille de 25mm (lamda/4)
Le boitier est une bonne antenne en émission et réception dans ces bandes de fréquence

11. Susceptibility Issues
Multiple parasitic electromagnetic sources
Components issues
Power HF
VHF
UHF
SHF
xHF
THF
1GW
Radar Météo
Radars
Satellites
1MW
TV UHF
MWave
1KW
TV VHF
Stat. de base
Badge
Hobby 1W
GSM
UMTS
Multitude de sources de puissance différente entre 30MHz et 30GHz => la bande de fréquence dangereuse est très large et les modes d’agression sont très varies (continu, impulsionnel), la distance à l’émetteur varie aussi du km au cm => problème complexe et de moins en moins déterministe (multiplicité de cas)
Radar
Hobby
DECT
1mW
Frequency
3 MHz
30 MHz
300 MHz
3 GHz
30 GHz
300 GHz

12. Immunity suddenly decreases? Immunity increases with Freq
Susceptibility Issues
Susceptibility trends vs frequency
Immunity suddenly decreases?
Immunity increases with Freq
Barber, Herke, IEE Electromagnetic Hazard, 1994

13. Susceptibility Issues
Desynchronization issues
Jitter is becoming increasingly important in design of logic circuit due to rising operating frequencies.
The increase of operating frequencies of digital circuits reduces their dynamic margin
EMI on supply
EMI induced jitter
Bit error
Dynamic failure
EMI induced jitter

14. Emission / Susceptibility Issues
Block type
Emission
Susceptibility
Fast digital I/O ++ -
Power switch output --
Oscillator / PLL / Clock circuitry
Charge pump
Digital block supply +
Analog input
DC/DC converter

15. EMC environment EMC for Integrated Circuits requires various expertise
High frequency measurement
High frequency modelling
2D, 3D modelling
Electrical modelling
IC design
IC floorplan
Caleidoscope du materiel etrange de la CEM

16. EMC Measurement methods

17. EMC measurement methods
Why EMC standard measurement methods
Check EMC compliance of ICs, equipments and systems
Comparison of EMC performances between different products, different technologies, designs, PCB routings
Improve interaction between customers and providers (same protocols, same set-up)

18. Radiated or conducted coupling
Emission measurement methods
Emission – General measurement set-up
Control - Acquisition
Coupling device
Coupling network
Antennas
Wave guide
Device under test
Radiated or conducted coupling
Acquisition system
Spectrum analyzer
EMI receiver
Oscilloscope
50Ω adapted path
Emission requirements verified ?

19. Emission measurement methods
International standards for IC emission measurement methods
IEC
(TEM : 1GHz)
IEC /6
(Near field scan, 5GHz)
IEC
(1/150 ohm, 1 GHz)
IEC
(WBFC, 1 GHz)
IEC
(Mode Stirred Chamber: 18 GHz)
(GTEM 18 GHz)
Gros travail de normalisation => cadrer et normaliser les méthodes de mesures, permet les comparaisons, permet la discussion entre client et fournisseur

20. Emission measurement methods
Example of emission measurement set-up – TEM cell measurement
Chip under test
Spectrum Analyzer
Shielding
Septum
Far end
(to absorb
ers 50 W
termination)
aperture 1
aperture 2
Near end (to receiver)
Pre-amplifier
GTEM cell
Emission spectrum

21. Immunity measurement methods
Immunity – General measurement set-up
Injected level Extraction
Failure detection
Disturbance generation
Harmonic signal
Transients
Burst
Coupling device
Coupling network
Antennas
Wave guide
50Ω adapted path
Radiated or conducted coupling
Device under test
Immunity requirements verified ?

22. Immunity measurement methods
International standards for IC susceptibility measurement methods
IEC
(Bulk Current Injection : 1 GHz)
IEC
(Direct Power Inj 1GHz)
IEC
(TEM/GTEM)
IEC
(WBFC 1 GHz)
New proposal:
(LIHA : 10 GHz)
Still research:
(NFS 10 GHz)

23. Susceptibility threshold
Immunity measurement methods
Example of immunity measurement set-up
Signal Synthesizer
Decoupling network
Chip under test
Failure detection
Pforw
Prefl
Directional coupler
DPI Capacitor
Amplifier
Oscilloscope
Acquisition card
Susceptibility threshold

24. Impedance extraction
Equipment to extract impedance profile of board, package, chip
Frequency domain
Time domain
Vector Network Analyzer
Time Domain Reflectometry

25. EMC equipments Expensive …. Complete EMC laboratory : 500 K€
Main equipments for EMC – typical prices
Vector Network Analyzer 10 GHz (100 K€)
Amplifier 3 GHz 100W (60 K€)
Spectrum analyzer 40 GHz (40 K€)
GTEM cell 18 GHz (15 K€)
Signal Synthesizer 6 GHz (20 K€)
Expensive ….
Complete EMC laboratory : 500 K€