You need both hardware & software to test next-gen RF device designs
01 May 2021
The insatiable thirst for data in the information age is pushing our communications networks into the millimetre frequency bands of 30 GHz & beyond. At these higher frequencies, wide bandwidths of 4-8 GHz enable faster data transmission.
The full version of this article was originally featured in EPDT's 2021 PXI for T&M supplement, included in the May 2021 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.
However, as Matt Campbell, Product Marketing Engineer for Network Analysers at electronics T&M expert, Keysight Technologies tells us here, there’s always a trade-off. As your bandwidth gets wider, your signal takes on more noise, decreasing your signal-to-noise ratio. In addition to dealing with lower signal-to-noise, you also need special considerations when measuring high-frequency devices. Non-connectorised, highly integrated multiport devices push the limits of traditional test equipment.
To keep up with the demands of modern device test, you need to make sure that your test setup is as integrated as your devices. Software applications simplify your workflow with advanced characterisation and measurements against the latest wireless standards on a single connection, while modular PXI instruments simplify your test setup and save significant time with connections and calibration.
More ports, more problems
Modern RF devices pack a lot of functionality into small packages. A smartphone has WiFi, Bluetooth, GPS, NFC and 4G, or even 5G, connectivity, all in a pocket-sized package. High device integration makes portable, flexible devices possible. Instead of testing individual components, RF engineers now test integrated sub-assemblies on PCBs or wafers. Increased
integration means increased port counts. For example, an antenna array will contain multiple beamformer modules. Each beamformer module contains a core integrated circuit with multiple front-end modules (FEM). Each FEM contains transmit/receive hardware like mixers, filters and amplifiers.
An antenna array contains hundreds of signal paths and thousands of components. N-port devices have N2 S-parameters, so a 24-port antenna has 576 S-parameters. If you have a 4-port network analyser and a 24-port device, you’ll need to perform 264 sweeps to characterise every possible path through your device. However, with a 24-port PXI network analyser, you can perform 24 sweeps simultaneously and get all your S-parameters in one step.
Switching away from switches
Switch-based setups traditionally performed multiport measurements. However, as frequencies increase, the drawbacks of switches have a more significant impact than just the number of sweeps.
Most switch-based solutions require configuration at the factory and are not easily customisable. Upgrading your switch setup means returning it to the manufacturer or completely replacing the setup. This process increases your cost of test with downtime and limits your flexibility.
Multiport solutions are fully scalable — meaning you buy only what you need and then upgrade at any time. Modern multiport VNA chassis support up to 50 ports in a single chassis, and you can start with just two ports and add as many as you need...
Read the full article in EPDT's May 2021 digital issue...
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