Evaluation Engineering - 9

Exceptionally wide dynamic range, low
DANL, high 1 dB compression point and
high third-order intercept are required
and expected.
"Standards in A&D (MIL-STD-461G)
and automotive (CISPR 12/25) are gaining relevance, and for amplifier designs,
device validation test (DVT) and product validation test (PVT) continue to
be strong. Frequency bands BC, D, and
E continue to be popular bands where a
lot of validation is happening. Coexistence
testing is also becoming increasingly
relevant for both designers and test labs.
With more potential interference around
any given device, it has become clear that
one not only needs to look at the operability and compliance of a single device,
but also at coexistence to other emitters.
Test labs are increasingly asked to also
test for coexistence. A fairly new trend for
broadband amplifiers is the ability to adjust the operating class during operation
so that one can optimally tune the output
signal to a specific application. During
operation, one can adjust the operating
class for transistors between Class A and
Class AB as well as choose between maximum output power or higher mismatch
tolerance at the output. Instruments with
such capabilities from Rohde & Schwarz
are the R&S ESR and R&S ESW for receivers, and the BBA130 for amplifiers.
"For power amplifiers, there is the continuous trend toward higher frequency
coverage with same output power and level of VSWR handling. Solid-state technology has become the de-facto standard for
broadband amplifiers and will eventually

replace TWT tube technology that has
poor reliability and production yields."
Bill Stumpf, technical & laboratory manager at D.L.S. Electronic Systems: "Since
FFT receivers have been accepted by
CISPR standards, we see a push toward
that capability in a continuing effort to
increase measurement speed. Software
and hardware functions are being added
to try to keep pace with advancing wireless technologies."

Challenges
As EMI/EMC technology continuously
evolves, so do its challenges thrust upon
vendors of such instruments. What key
challenges are vendors of EMI/EMC receiver & amplifier facing today?
Stinson and Krauska, Tektronix: "Increasing clock speeds and the proliferation
of wireless connectivity in IoT devices
means that emissions are becoming higher in frequency and in some cases intermittent or with a time varying behavior.
This presents several changes in terms of
detection-with a lot of receivers having
a traditional maximum range of 1 GHz
and sweep speeds that will miss many
intermittent or time-varying events."
Cline, Rohde & Schwarz: "For receivers,
providing wider bandwidths and higher
frequency coverage continue to be major drivers. In addition to the hardware
performance as described above, it has
become crucial for vendors to also support their customers with tools and capabilities that give
more insight into
possible interferers. This also puts
additional focus
on usability aspects of EMI receivers. Today's
instruments not
only need to meet

An engineer
performing EMI debug
troubleshooting a
Tektronix real-time
spectrum analyzer.

and exceed the required hardware specifications, but they also need to come
equipped with a variety of capabilities
and an intuitive user interface that helps
customers to go beyond pass/fail results
to really understand where potential interferers are coming from.
"Complete EMC solutions are also
becoming more complex; it is no longer
sufficient to design a system for just one
standard. Customers need the ability to
test against multiple standards including
ANSI, ETSI, and FCC. Coexistence tests
are also becoming more relevant and a
requirement for many customers. As a
supplier, it is important to be able to offer a complete system of instrumentation
including receivers, amplifiers, generators
and other accessories designed for the use
case of that customer."
Stumpf, D.L.S.: "Keeping pace with advancing wireless technologies and associated test standards is a constant and difficult challenge for EMC test equipment
manufacturers and test labs. As wireless
and other product operating frequencies
go higher so will the requirements of EMC
measurements."

What are customers asking for?
Here are the features and other innovations today's EMI/EMC receiver & amplifier customers are asking vendors to
provide.
Stinson and Krauska, Tektronix: "As mentioned earlier, real-time capability over
traditional swept significantly increases
the likelihood of observing and recording short-duration events. In addition to
near-field E- and H-field probes, customers are asking for support of calibrated
current probes-for measuring transient
common-mode currents along cables and
I/O ports. Customers are also asking for
support of near-field TEM cells (TEM/
GTEM/Crawford Cells) for desktopsize EMC testing. Low cost RF-shielded
tents have also become very popular for
precompliance."
Cline, Rohde & Schwarz: "Receivers:
Generally, customers are always faced
with wider measurement bandwidth and
JULY 2019 EVALUATIONENGINEERING.COM

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Evaluation Engineering

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