How a new generation of Vector Network Analyzers offers more testing options

Vector Network analyzers (VNAs) are an essential part of RF testing, as they allow designers to assess signal parameters and measure the performance of components and circuits across a variety of complex systems.

With a wide variety of analytical functions available across different models of vector network analyzers, they enable a number of components to be tested in detail — from high end VNAs that allow for amplifier and mixer measurements, to affordable handheld devices that provide support for spectrum analysis and power measurements.

This blog post takes a closer look at the wider testing options introduced by a new generation of vector network analyzers.

Using vector network analyzers

 Vector network analyzers have been widely used across the industry for component testing and help to achieve more accurate characterization through measuring the amplitude and phase of swept-frequency test signals.

VNAs can be used to plot the amplitude and phase of a signal over a period of time – this information allows troubleshooters to assess a signal’s behavior and identify how it is being transmitted and reflected. Doing this can help to characterize signal scattering – a key issue that can impact the performance of a component.

Finding greater precision

 Existing VNAs have a high degree of accuracy already, but with the addition of lasers, their function can be improved to enable greater precision in measuring signal strength and phase in components.

With a more complex structure, the new generation of prototype analyzers exceeds frequencies of 1THz. The enhanced precision of new network analyzers is due to the use of a femtosecond laser to generate test signals – using short and precise voltage pulses that are passed down a short gold strip of 4mm length, the electric field of a gallium arsenide chip can be changed. Another laser beam subsequently tracks and measures changes in phase and amplitude as the signal progresses.

This technique allows for greater precision in measurement, as it can resolve both signals travelling up and down, and additionally measure their reflection.  By measuring voltage pulses at different positions, designers are able to separate voltage signals in both directions, even when signals are temporarily overlapped. Taking these values over a range of frequencies enables designers to characterize the device under test comprehensively.

However, while femtosecond lasers are low in price and simple to install, the new generation of analyzers is not entirely free of drawbacks. Its most obvious limitation is a smaller dynamic range – while conventional VNAs have a range of 120 dB, these are restricted to 40 dB, despite having a measurement bandwidth of 500 GHz.

Nevertheless, their overall simplicity and the broad frequency range accessible through a single piece of hardware is a significant advantage, and they are likely to continue to grow in usage.

What are your thoughts on the new generation of VNAs? Do you prefer to use more standard analyzers, or will these give you an advantage? We’d love to read your thoughts – share them with us in the comments!



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