Evaluation Engineering - 18

RF TEST

INSTRUMENTS OFFER MULTIPLE
FORMFACTORS, FUNCTIONS
By Rick Nelson, Interim Chief Editor
Instruments come in a variety of
formfactors, letting you trade-off the
performance you need that fits in the
space you have available. Typical configurations include benchtop (such as the
Rohde & Schwarz SMW200A vector signal
generator), portable (such as the portable
version of the Tabor Lucid RF signal generator), and PXIe or PCIe (such as the
SPECTRUM Instrumentation M2p.65xx
Series PCIe waveform generator). Many
instruments come with multiple functions-combining an oscilloscope with a
signal generator, for example.
While responding to requests for input
for last month's report on signal generators,1 instrument makers also commented on the tradeoffs involved in various
formfactors and multiple-instrument
functionality.

Multiple configurations
Signal generators come in a variety
of configurations, such as traditional
benchtop instruments, handheld instruments with display, USB instruments,
and PXI modules. What are the advantages and disadvantages of each?
Brandon Malatest, founder and CEO of
Per Vices Corp.: The different configurations available each meet unique needs for
different applications. Traditional benchtop instruments are still the most common and offer engineers the best overall
solution when comparing performance,
cost, and usability. These systems are the
best option for R&D use where access to
high-performance equipment is needed.
The drawbacks for these systems are typically a combination of portability, size,
and power consumption.
Steve Sandler, founder and CEO of
Picotest: Tradeoffs are made in each configuration. The bigger question is about
user demand, which is looking to see a

EVALUATION ENGINEERING DECEMBER 2019

Rohde & Schwarz SMW200A benchtop vector signal generator.

single GUI interface and preferably an allin-one instrument. You can see evidence
of this primarily from the oscilloscope
manufacturers, which all now include
frequency-response-analyzer functionality using built-in signal generators..
Oliver Rovini, technical director of
SPECTRUM Instrumentation GmbH:
We see three different main classes here.
First, benchtop instruments with a display and full manual control are best for
everyday work at the lab with changing
and individual demand. Second, modular instruments based on a common bus
system like PCIe or PXI are the best fit
for integrated devices or OEM products.
Third, [we see] external instruments that
are operated by a PC via Ethernet or USB.
Simon Ache, director of signal generation product management at Rohde &
Schwarz: The number of use cases for
signal generators are manifold, and so
are the sizes and configurations. Small,
self-contained, modular, and faceless signal generators can be operated via USB
or LAN, offering space and performance
advantages in remote-controlled applications. At the same time, they avoid incompatibilities that might occur when using

PXI-based signal-generation cards of vendor A together with modules of vendor B
in a PXI chassis of vendor C. Handheld
generators are good for field use, but
battery up-time is often low. Benchtop
instruments are available in the most
diverse sizes and performance classes.
Jon Semancik, director of marketing at
Marvin Test Solutions: Interfaces such
as USB and LXI are typically used in
rackmount box solutions, which do not
have the size restrictions found in cardbased solutions. This simplifies the task
of component placement and shielding
but also increases the overall footprint
of the solution. PXI certainly reduces the
size of the solution, but the added space
and size restrictions place demands on
the designer to carefully consider component placement and shielding.
Kimberly Cassacia, Sean Lee, and Xiaowei
Zhang, signal-generator product managers, and Eric Hsu, signal-generator product
marketing manager, Keysight Technologies:
Benchtop signal generators are well suited
for R&D or design verification, where analysis and troubleshooting benefit from interactive analysis. Modular PXI signal generators are ideal for applications that require

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