Programmable RF Components in Automated Test Equipment (ATE)

Posted by Scott Blanchard on Mar 24, 2016 3:00:00 PM

Programmable_RF_Components_ATE_600px.jpg

In the past, large production environments and sophisticated labs were the dominant influence on the research and development that led to yesterday’s full-featured benchtop equipment market. Today, however, nimble test and verification teams are increasingly looking for more portable and cost efficient solutions devoid of cluttered GPIB cabling and specialized software. Not only has the debugging of previous generation automated test equipment (ATE) proven difficult without expert technicians, test engineers today are enjoying the flexibility of using programmable components that leverage APIs connected to commonly used software platforms. 

Hands-Off Testing

ATE can range from very simplistic tests, leveraging a small amount of equipment, to large complex tests, complete with a probing station, pneumatics automation, tape-and-reel feeders, and robotic automation. Nonetheless, PC-driven active components in any test setup can offer great advantages over traditional semi-automatic or manually driven test benches. In the RF world, test equipment such as vector network analyzers (VNA) or spectrum analyzers have a limited amount of receiving ports. This can increase the number of physical adjustments to a setup in order to obtain all the probing permutations necessary to fully test a multi-port device under test (DUT).

Going through all these test setup permutations inevitably adds cost and time. For example, testing an 8-way RF switch with a total of 9 ports would require a large number of test iterations to gather all 81 s-parameters. This test can be labor intensive without an automated switch box. The switch box would test every individual s-parameter of the DUT through a preprogrammed arrangement of internal switches, and the 2-4 ports of a standard VNA would suffice to test all 81 parameters in one test iteration.

Automatically Driving Individual Components

Commonly used RF components in test benches include phase shifters, RF switches, and digital attenuators. More complex test equipment, such as VNAs, signal generators, pulse generators, and power meters, are also found on almost every RF and Microwave test bench. Normally, RF components require manual control for a particular output, and test equipment data needs significant reformatting to be usable for analyzing and sharing data. For example, digital attenuators have traditionally been controlled by transistor transistor logic (TTL) where a low voltage would yield a logic level of 0 and a high voltage would yield a logic level of 1. These logic levels determine the path leveraged in a digital attenuator to yield a desired attenuation. This method required complex programming, TTL drivers and a large number of interconnects.  Today, with USB devices such as the Lab Brick Digital Attenuator, this complexity is eliminated.  Attenuation levels can be directly programmed without the clutter of TTL connections all through the single USB connection.  Did we mention it’s also powered through the USB port? Further reducing complexity and clutter.

Benefits of Integrated Software

Oftentimes a test may require an engineer to monitor and adjust a wide variety of outputs for their desired measurements. Tracking all the knobs, buttons, adapters, and plugs can sometimes be complex and prone to human error. The ability to assimilate and analyze data concurrently helps design and test engineers readily assess the performance of a DUT that may fail specification. Vaunix lab bricks offer a pre-existing software platform with a guide that walks through the test and measurement process.  This way, making adjustments to a test bench is simplified and much more easily tracked from one controller, a laptop or computer.

Lab Bricks

Vaunix offers programmable USB-driven lab bricks that have an original Vaunix Graphical User Interface (GUI), Windows dll files, Linux and labVIEW compatible drivers. These rectangular-shaped components are a welcomed solution for test benches. With Vaunix now offering USB-driven signal generators, digital attenuators, RF switches, and phase shifters—these components can be a puzzle piece to almost any automated test setup. All components can be held in the palm of a hand allowing for more real estate for these often cable-cluttered benches.

Topics: Signal Generators, Lab Brick, digital attenuators, test and measurement, ATE