The latest trend in PXI is…boxes!

-May 13, 2014

Modules versus boxes has been a debate going on in ATE circles since the time of the mods and rockers.  Modular PXI systems are fast, small, and offer increasing parametric performance.  Traditional “box” instruments are easy to use, portable, and offer front panels and displays for manual bench operation.  The two formats orbit around different value propositions.  But the latest trend is the increasing use of PXI to create one-box testers and traditional bench instrumentation.  In this column I talk with seven companies, and get their unique perspectives on this topic.

Agilent Technologies

What got me thinking about this was Agilent Technologies’ latest OBT (One Box Tester) for wireless communications, the EXM Wireless Test Set.  Looking at the product, which is Agilent’s latest salvo to address the manufacturing of cell phones and other cellular appliances, it became obvious that it was a PXI system inside.   Speaking with Mike Griffin, Product Marketing Manager for Agilent’s wireless test business, he explained the strategy.  PXI was chosen as a compelling architectural path since it offered time to market by leveraging the chassis, controller, and existing PXI modules, but could also be updated by adding new instruments.  In this case, Agilent designed high density PXI “TRX” (transmit and receive) modules that allow four transmit and receive channels within each OBT.  

Figure above shows Agilent Connectivity Test Set on left, and EXM Wireless Test Set on right. Both are PXI-based internally.

The EXM follows on the heels of another “box from modules” tester from Agilent, the Wireless Connectivity Test Set, which focused on WLAN and Bluetooth.  Mike described the customer benefits of this approach to be those one expects from a modular system: speed, density, scalability, and flexibility. Ease of integration is accomplished by set combinations of functionality coming pre-configured, such as the number of channels, bandwidth, and frequency range.  Most importantly, the product comes prewired to a customer facing front panel that includes Type N and BNC connectors, delivering a ruggedized interface for the manufacturing floor.  Clearly a vendor advantage to this approach is that the modules may have dual use- addressing “roll your own” systems as well as these pre-integrated OBTs.


My next conversation was with Chris Ziomek, General Manager of Design Test Solutions at LitePoint.  Astute readers may recall my interview with him as president of ZTEC Instruments.  More recently, this column broke the inside story behind LitePoint’s acquisition of ZTEC, itself acquired by Teradyne.  Since that time, the ZTEC RF products, all PXI, have become the zSeries Test Solutions for the RF Lab under LitePoint.  While the products may still be purchased as individual modules, there’s no hiding that LitePoint is principally promoting the “one box” solutions for power amp test, RFIC test, and MIMO (Modular Instruments Meet Opportunity Multiple Input Multiple Output).  Chris thought the MIMO solution best exemplified the customer and vendor advantages of a “PXI-inside” approach.

ZTEC zSeries MIMO solution is shown on the left (configured for 4x4 MIMO) with analysis software shown on the right.

Customers like the open standard “mix and match” capability of PXI.  Like PXI, MIMO is a naturally modular architecture, so vendors can easily pre-configure systems for MxN channels, matching the customer’s applications. PXI brings fast time to market, not just due to internal leverage, but also by integrating another vendor’s product into the instrument, such as MIPI or SPI interfaces.

There are tradeoffs. Chris said that the overhead of PXI internally adds significant cost as compared to a custom integrated solution.  This is most important in high-volume applications.  This explicit trade-off of time to market versus lowest cost is reflected in LitePoint’s targeting: PXI-based zSeries is focused on design verification where time to market is critical, while LitePoint offers the internally optimized IQ Series for manufacturing applications.  


I was able to schedule an interview with Phil Medd, Wireless Communications Product Manager at Aeroflex.  Like Agilent and LitePoint, Aeroflex offers one-box testers for wireless communications, the most recent being a one-box solution for base station manufacturing test, based on PXI.  But it is the Aeroflex 7100 Digital Radio Test Set that is the real format bender.  

The image above shows the Aeroflex 7100 surrounded by common applications.

The 7100 looks like a traditional bench instrument, complete with an embedded touchscreen display.  Pop the covers off and, yes, its PXI. At least the front end instrumentation is, leveraged from the Aeroflex 3000 series.  An embedded Windows PC drives the touch panel human interface, while a dedicated DSP subsystem supplies the digital signal processing.  Phil credited the PXI strategy as helping time to market- the entire project took less than one year from concept to shipments.  Numerous applications are enabled by leveraging the Aeroflex measurement libraries, and the inherent modularity allows plenty of options, including MIMO.  Recent announcements have added the LTE-U band, an unlicensed band that can be as high as 5 GHz.  Aeroflex is creating a single channel version for service applications, an application where technicians may prefer the embedded box format.

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