Automotive IC-Level EMC
Testing—Trends and
Forthcoming Standards
Stephan Gerlach, Juergen Strohal
Standardization activities focused on electromagnetic compatibility (EMC) at the IC level have been
evolving to keep pace with potential current and future interference scenarios. This article describes
forthcoming new test standards such as local injection horn antenna for covering such higher operation
frequencies as WLAN and Bluetooth. In addition, this paper identifies new trends in electromagnetic
surface scanning.
Each day, EMC labs that deal with compliance measurements for certification and validation carry out a
variety of well-known methods and techniques to investigate unintended emissions by complete vehicles
or modules in violation of specifications.
Within these devices under test—mostly modules with a certain functionality as well as input and output lines—there is a
Automotive Compilation Vol. 9
in the IC itself. In general it is both important and very useful to
know the maximum disturbance level coming from the IC itself
if it is operated in an environment optimized with regard to
EMC considerations.
long-term trend emerging: the concentration of functionality
within an ever smaller number of “active” devices. This trend
is primarily driven by two important factors.
First, there is the increasing level of integration seen in
IC functionality on a single chip and, second, the ability of
integrated processes to implement functionality previously
reserved for external blocks. This feature, initially welcome,
increases the level of disturbance that can be produced by a
tiny amount of silicon housed in a small plastic package.
IC Stripline
The stripline method is a well-known standard for use in a
component (module) level test according to ISO11452, with
the wiring harness placed inside a widened stripline. Recently,
this method has been less frequently used for homologation
(usually the ALSE method is preferred); however, it is still a
fairly easy-to-use instrument for evaluative measurements. The
basic setup can be seen in Figure 1.
This being said, the techniques for investigating signal source
interference must logically concentrate on the device with the
highest potential for interference.
As most of the established test standards are limited to
frequencies up to 1GHz, or in the best case 2GHz, there has
been a greater and greater need to cover frequencies up
to 3GHz or even higher with reliable and reproducible test
methods. Various standardization committees have devoted
time to developing such standards; two of them, the “IC
Stripline” and “Local Injection Horn Antenna”, are briefly
introduced in this paper. Another helpful instrument for locating
sources of distortion, even at the sub-IC level, are the proven
techniques and methods for PCB scanning, which have been
adopted by the industry and greatly improved.
The reason for carrying out EMC evaluation at the IC level is
quite comprehensive: A complete system (mainly a module)
has to meet the filed requirements so that it is very timeconsuming for application engineers to find out in detail the root
cause for a specification violation—whether it originated in the
board, the peripheral connectors, the passive components, the
arrangement of the components, GND layer management, or
The new, forthcoming IC stripline standards take this approach
down to the IC level. Both aspects of radiated EMC tests are
covered; IEC61967-8 contains the emission measurements
while IEC62132-8 standardizes immunity measurements. In
contrast to the ISO11452 stripline measurement, the IC stripline
does not contain a wiring harness but instead covers the IC
under test. For this purpose the IC stripline is dimensioned
according to the width and height requirements. These
two parameters must be chosen interdependently in order
to maintain stable conditions over the complete operation
frequency range from 150kHz up to 3GHz with VSWR<1.25.
The default height (spacing between active conductor and
ground plane) is 6.7mm with a default width of 33mm. The
DUT’s dimension should not exceed half the height of the
stripline, and its width should not exceed 110% of the stripline’s
width. The standards documentation provides information
on correct dimensioning of the IC stripline. Figures 2 and 3
show the respective test setups for emission and immunity
measurements.
DUT
(Cable Harness)
(Styrofoam)
Periphery
50Ω Termination
Artificial Networks
Directional Coupler
Figure 1. Basic Set-Up for Stripline EMC Testing According to ISO11452-5
© 2012 / www.atmel.com
DUT Stimulation
and Monitor
Power Supply
The test bench and proceedings are regulated in IEC 62132-6.
Spectrum Analyzer/
EMI Receiver
Shielded Chamber
Port 2
(RF Connector)
EMC Test
Board
Preamplifier
(if Necessary)
Antenna
Feed
Horn Antenna
E Field
Port 1
(RF Connector)
IC Stripline
DUT
50Ω
Termination
IC
under
Test
H Field
Figure 2. Setup for Emission Measurements with IC Stripline According to IEC 61967-8
Ground Plane
Figure 4. Internal Assembly of EMC Chamber with Local Horn Antenna Injection
RF Generator
DUT Stimulation
and Monitor
Power Supply
RF Amplifier
Pforward
Power Meter
Preverse
EMC Test
Board
Port 2
(RF Connector)
Scanning systems mostly consist of a near field probe, spectrum
analyzer, xyz-moving table, and a computer with software for
mechanical steering as well as analysis and interpretation.
Precise calibration and test system repeatability are important
criteria, in particular in the micrometer range, and should not be
underestimated.
Directional
Coupler
Port 1
(RF Connector)
IC-based Scanning
IC Stripline
DUT
50Ω
Termination
The results of such measurements can be visualized as two or
three-dimensional colored plots.
Figure 3. Setup for Immunity Measurements with IC Stripline According to IEC 62132-8
Local Injection Horn Antenna
Another approach to extend test standards on the IC level
toward higher frequencies is the local injection horn antenna.
Typically, the ICs under test are only equipped with minimum
external circuitry (blocking capacitors) mounted on a small
PCB. The disturber is applied to the IC surface by means
of a specially designed horn antenna that creates a strong,
concentrated E and H field with a high degree of homogeneity.
That means the field strength deviation is less than 3dB
throughout the surface of the IC.
Regarding radiated immunity, a standard is under development
that uses a horn antenna in the 1GHz to 18GHz frequency
range. The IC is exposed to the antenna’s electrical field, which
is arranged at right angles to the DUT. The magnetic field
deflects circularly around the IC.
Automotive Compilation Vol. 9
Figure 5. Courtesy of: Detectus AB, Malung, Sweden
Field Probes
Figure 6. E-Field Probe for IC-Level
Measurements
Several electric and magnetic field probes for IC-based
measurement are already available on the market. Magnetic
field probes are equipped with vertical and horizontal coils.
The mechanical resolution is 65μm for the E-field probe and
80μm to 100μm for the H-field probes; they can be used within
a frequency range of 30MHz to 3GHz. H-field probes with a
low-frequency range from 9kHz to 50MHz are available for
specific applications.
Figure 7. H-Field Probe for IC-Level
Measurements; Vertical Coil with an Inside
Diameter of 150μm
The reason IC-based scanning is used is because of the basic
rule that the EMC disturbing levels of the complete module
should never fall below the reference values of the applied IC
(optimum blocking provided).
This being said, it is essential that ICs are measured and
compared before making a decision which could have a
significant and long-lasting impact on technical performance.
A wide variety of IC-level test methods has been available
for unwanted electromagnetic emissions and electromagnetic
distortion susceptibility for over ten years. These standards are
well established and widely used in the automotive industry
to indicate how critical the application of a particular IC might
be in terms of EMC, and how much external effort is required
to achieve EMC compliance. Choosing the appropriate ICs with
superior EMC performance at the very beginning of a project
helps to avoid subsequent and expensive corrective measures.
Figure 8. H-Field Probe for IC-Level
Measurements; Horizontal Coil with an Inside
Diameter of 150μm
Graphics by Langer EMV www.langer-emv.com.
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© 2012 Atmel Corporation. All rights reserved. / Rev.: Atmel-Article-AC9-Automotive-IC-Level-EMC-Testing_V2_042015
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