Hittite Microwave Reduces RF Integrated Circuit Test Cost and Improves Test Speed Using the NI PXI Vector Signal Transceiver and Instrument Driver FPGA Extensions

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"With the NI vector signal transceiver, instrument driver FPGA extensions, and the rest of the PXI platform, NI provides us with the cutting edge test solution we need to keep test costs low and stay competitive within our industry."

- Hittite Microwave Corporation,

The Challenge:
New RF components with increasing functionality and features require high-performance RF test instrumentation that is easy to use as well as highly flexible and customizable to reduce test time and cost.

The Solution:
Engineers at Hittite Microwave Corporation used instrument driver FPGA extensions to take advantage of the existing RF and baseband I/Q analysis and generation capabilities of the software-designed NI PXIe-5645R vector signal transceiver while modifying the user-programmable FPGA to implement custom signal processing and digital device under test (DUT) control.

Hittite Microwave Corporation -

Hittite Microwave Corporation

Hittite Microwave Corporation designs and manufactures high-performance ICs, modules, subsystems, and instrumentation for technically demanding digital, RF, microwave, and millimeter wave applications covering DC to 110 GHz. The company's standard and custom products apply analog, digital, and mixed-signal semiconductor technologies, which are used in a wide variety of wireless and wired communication and sensor applications for the automotive, broadband, cellular infrastructure, fiber optics and networking, microwave and millimeter wave communications, military, test and measurement, and space markets.

Advancements in Product Design Require Advancements in Test

At Hittite, our latest RFICs and multichip modules (MCMs) provide our customers with more features and higher performance than ever before, but this increase in performance also adds to the complexity and cost of testing these devices. These modules feature multiple transmit and receive paths with differential I/Q baseband I/O. Additionally, these modules contain multiple internal RF filters, modulators, amplifiers, digital-to-analog converters (DACs), analog-to-digital converters (ADCs), and more. The NI PXIe-5645R vector signal transceiver combines a vector signal analyzer, a vector signal generator, I/Q baseband I/O, and digital I/O in a single 4-slot PXI Express module, which makes it the ideal instrument for testing our RFICs and MCMs.

Fully testing these modules with traditional rack and stack test instruments in a multiple-input, multiple-output (MIMO) configuration would be cumbersome and expensive, and would require complex cabling and fixturing. By contrast, the NI vector signal transceiver easily expands to support MIMO test applications in a single PXI Express chassis, and we can easily integrate additional NI PXI instruments into a single backplane. For example, we added several NI PXIe-4145 power supplies to the system without consuming any additional rack space. Furthermore, the NI PXI test system costs less overall when compared to traditional rack and stack instruments.

Vector Signal Transceiver FPGA Customizations for Higher Test System Performance

The NI vector signal transceiver’s compact size and high analog performance make it an excellent fit for our RF test application, but the unique ability to program its FPGA using NI LabVIEW system design software truly revolutionizes our testing. The instrument driver FPGA extensions for the standard RF signal analyzer and RF signal generator instrument drivers help us to customize the vector signal transceiver. FPGA while still preserving all of the hardware and software functionality we expect from our RF test equipment.

We control most of our devices through the digital Serial Peripheral Interface (SPI) protocol, in addition to many components on our load board. We use LabVIEW FPGA SPI intellectual property from NI to control multiple devices through the digital I/O port on the vector signal transceiver. Most device control is for the MCM, w hich includes integrated filters, attenuators, switches, and amplifiers, and results in a significant number of permutations and tests that we need to run. Implementing custom device control on the VST FPGA helped us reduce our overall test time by more than 30x, compared with our previous rack and stack test setup. By using instrument driver FPGA extensions, we made only a minor modification to the FPGA in LabVIEW and kept compatibility with the standard instrument drivers. This greatly reduced the development time necessary for a project with customized firmware, and we were still able to take advantage of the complete functionality of the proven NI RF instrument drivers.

Not only did NI provide us with revolutionary test hardware and software for this project, but systems engineers from the company supported us during the development process to ensure we met our schedule.

Future Possibilities With Software-Designed Instrumentation

We have just begun working with the user-programmable FPGA on the NI PXIe-5645R vector signal transceiver. Looking forward, we see many additional possibilities to use instrument driver FPGA extensions, including DUT control, custom triggering, limit comparisons, and reductions in the amount of data we transfer to the host for processing. By implementing signal processing on the FPGA, we can accelerate operations we frequently perform, such as power, frequency, and other measurements, to further reduce our test times.

In addition, the flexible NI test platform can test many device types, which helps us to preserve our hardware investment by reusing it for future products. We need a scalable platform that can handle the increased complexity we will see in the next five years and beyond. With the NI vector signal transceiver, instrument driver FPGA extensions, and the rest of the PXI platform, NI provides us with the cutting edge test solution we need to keep test costs low and stay competitive within our industry.

NI Contacts: Erik Johnson and Ryan Verret

Author Information:
Hittite Microwave Corporation

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