Written by Stuart Rumley, Valon Technology, LLC
Lord Kelvin was right: If you can't measure it, you don't know what you're talking about.
The key to designing and manufacturing high-quality electronic equipment is the ability to make measurements on various parameters accurately, repeatedly, and quickly. With signal sources such as oscillators, VCOs, TCXOs, and frequency synthesizers, no parameter is more important that signal purity. The Holy Grail of signal purity is PHASE NOISE.
The hardest measurement on the bench
Phase noise however is one of the most difficult of all electrical phenomenon to test and measure. Typically, it can be observed using direct measurement techniques with spectrum analyzers. Some advanced spectrum analyzers will even have a built-in phase noise analysis function. However, even the best spectrum testers have limitations on making close-in, low-level phase noise measurements accurately. The problem with making phase noise measurements using a spectrum analyzer on precision signal sources is not knowing what the contribution of the spectrum analyzer is on the observed measured phase noise. Or said another way, how do you know if the phase noise you measure is your measurement instrument or the DUT (device under test)?
Why cross-correlation earned a place on the bench
Fortunately, some brilliant mathematicians (magicians) and electrical engineers (wizards) figured out a system of measurement using a technique called "cross-correlation" that systematically removes the noise contribution of the measurement equipment. Genius! Unfortunately, these boxes come at a hefty price. They are often as expensive as the best spectrum analyzers in the same frequency space.
Here at Valon Technology we are committed to providing the best products we can, so we invested in this cross-correlation technology. Having this test tool on the bench allows us to optimize our product design. We discern such nuanced effects such as how a voltage regulator can affect the phase noise or what is the optimum signal level to drive a phase tester (high) to get the best performance.
Our engineering bench uses the Berkeley Nucleonics 7300 series Signal Source Analyzer to help us ensure we are squeezing all the squeaks and fuzz out of our frequency synthesizers and dividers. That is why we stand by our product performance.
Discuss your phase noise measurement
Berkeley Nucleonics builds the 7000 Series phase noise analyzers and signal source analyzers, and offers them for sale and rent for demanding RF work. To match an instrument to your application, request a quote or demo.