Test Connections - March 2017

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User Programmable FPGAs

Field Programmable Gate Arrays (FPGAs) are an integral part of today’s electronic products. Marvin Test Solutions’ FPGA products offer users the flexibility to create high-performance, customized PXI instrumentation for both digital and mixed-signal applications.

To a large degree, FPGAs have replaced custom and semi-custom ASICs – allowing the creation of high performance products without requiring the high investment / design costs associated with ASICs. The low investment / high performance attributes of FPGAs make these devices ideal for creating advanced instrumentation and more specifically, card modular PXI products that offer both performance and high functionality.
GX3788

FPGA Technology - A Key Enabler for PXI Products

The advanced technologies available to PXI vendors have been the catalyst for creating card modular products with capabilities and performance that rival and even surpass traditional "box" instrument capabilities. The explosive growth of FPGA technology and highly integrated mixed signal ICs has resulted in the availability of advanced digital instrumentation as well as user programmable FPGA products. For example, today’s advanced PXI digital instrumentation offers both PMU and digital test functionality in a single 3U PXI module (Figure 1), providing the capabilities to cost-effectively test semiconductor devices as well as providing the basis for a complete semiconductor test system (Figure 2) which can support up to 512 digital test channels in a compact, bench top configuration.  Similarly, FPGAs have enabled the creation of very high channel count, 3U PXI products (figure 3) that support 64 arbitrary waveform channels, providing users with the ability to simulate high channel count sensors for system test applications.

Digital Instrument with PMU
PXI Semiconductor Test System
64-Channel AWG
Figure 1: Digital Instrument with PMU
Figure 2: PXI Semiconductor Test System
Figure 3: 64-Channel AWG

FGPA Technology for Test Engineers

FPGA technology has also found its way into the hands of test engineers. FPGA - based cPCI products have been available for a number of years and typically have been used by design engineers as part of an embedded system design. However, the design tools for these products and the integration of these products into an overall system has been complex and time-consuming, limiting their adoption within the test engineering domain. However, today’s user programmable FPGA cards are allowing test engineers to create their own custom instruments without the complexities normally associated with FPGA design and integration.

Marvin Test Solutions offers a range of user programmable FPGA products that employ Altera FPGAs. All of these products employ a base board / user-defined daughter board architecture (Figure 4), allowing users to create their own custom analog or digital interface circuitry.

FPGA Card with Expansion Board


Figure 4: PXIe FPGA Card with Base Board and Daughter Card


As shown in Figure 4, users can create their own custom circuitry or 3U PXI / PXIe instrument by designing a custom expansion board for their specific application without resorting to bulky, external interface boards.  And since the daughter board and associated front panel connections are integral to the board’s design, users have the freedom to choose multi-pin or coaxial connections, depending on the application. Alternatively, the user can elect to use the supplied generic expansion board which provides access to the FPGA’s I/O via (4) 68 pin SCSI 3 interfaces located at the front panel of the card.

To simplify the overall design and integration process, MTS’ PXI FPGA cards also offer the following features and capabilities supporting full PXI functionality:
  • On-board 80 MHz oscillator for use as an FPGA timing reference
  • Access to the 10 MHz PXI clock and the 100 MHz PXIe clock (for PXIe FPGA version)
  • Access to all PXI trigger and local bus signals

Programming and integration of PXI FPGA cards has also been simplified by partitioning the user FPGA separate from the PCI interface - eliminating the need for the user to incorporate the PCI interface as part of his or her overall FPGA design. As Shown Figure 5, all MTS FPGA cards employ this partitioned architecture.

FPGA PXI Architecture


Figure 5: FPGA PXI Architecture


For the design of the FPGA, users can employ Altera's free Quartus II Web Edition tool set which supports all of MTS’ FPGA cards. And  for more complex designs, users can employ Altera’s Quartus II subscription edition software. Both schematic entry and VHDL methods are supported.  Once the FPGA design is compiled, the configuration file can be loaded into the FPGA via the PXI bus interface or via an on-board 16MB EEPROM - providing users with an easy way to incrementally design / test / modify their FPGA code. In addition, all MTS FPGA cards are  supplied with both an API and an interactive UI, facilitating loading of the compiled design.  Additionally, predefined registers are used to provide control and monitoring of the user FPGA’s functions - simplifying overall development and deployment of the design. The result is a user FPGA card that is easy to develop while offering the flexibility and performance associated with FPGA-based designs coupled with the standardization and open architecture of the PXI platform.

Today’s user programmable FPGAs offer test engineers the flexibility to design specialized and complex test instrumentation. With simplified design tools and instrument architectures, it is now possible to create custom instrumentation and designs that can address a range of application specific digital and analog test applications.

For product information and data sheets, please visit our web site.

To learn more about uses and advantages of FPGAs, visit Marvin Test Solutions' online Knowledge Base to download informative articles and white papers that address FPGA technology.