Phase Noise Source & Analyzer

So I Bought a Phase Noise Analyzer for Very Serious Professional Reasons...

There comes a point in every RF engineer’s life when normal test equipment stops being enough.

I have far crossed that line and more...

My latest bench additions are a PN2060D cross-correlation phase noise analyzer, covering 1 MHz to 7 GHz, and a Signal Hound PNCS-1 1 GHz phase noise standard to give me a known low-phase-noise source to measure against.

PN2060D phase noise analyzer and Signal Hound PNCS-1 on the bench.

I could pretend this acquisition was driven entirely by a carefully considered technical requirement. That would make for a respectable engineering blog post.

The actual motivation was much simpler:

Resume building and clout.

Seriously.

I wanted practical experience with phase-noise measurements beyond looking at plots in datasheets, papers, and application notes. Phase noise is one of those subjects where having access to the actual instrumentation changes your understanding considerably. It is one thing to know what dBc/Hz means or to calculate integrated jitter; it is another to have an oscillator on the bench and actually watch the measurement disappear into the analyzer’s noise floor.

But there was also a much less academically defensible motivation.

I saw someone on Twitter overseas discussing the PNCS-1 and the fact that they couldn’t easily buy one.

My immediate, completely mature response was essentially:

“Wait, I can buy one.”

And thus another entirely reasonable test-equipment purchase was born.

Firmly Past Hobbyist Territory

The resulting setup is somewhat absurd for a home electronics lab.

The PN2060D uses cross-correlation to suppress the analyzer’s own internal noise and dig substantially farther into the phase noise of a device under test. Paired with the PNCS-1, I now have a convenient 1 GHz source whose performance is good enough to start answering the much more interesting question:

Can I actually measure what the manufacturer says I should?

On one of my first real runs, I measured the PNCS-1 at approximately:

• −153 dBc/Hz at 1 MHz offset
• 5.29 fs RMS jitter from 12 kHz to 1 MHz

More importantly, the PN2060D’s measurement floor was comfortably beneath the source over the region I was interested in.

That is the fun part.

We’re no longer talking about using a spectrum analyzer to squint at skirts around a carrier and calling it a phase-noise measurement. This setup gets me into the territory of characterizing low-noise oscillators, PLLs, synthesizers, clock sources, and RF systems where close-in noise and femtosecond-level timing jitter actually matter.

Is This Overkill?

Absolutely.

That’s kind of the point.

I’ve always liked acquiring test equipment that gives me access to a measurement capability I didn’t previously have. A better oscilloscope is useful, but it usually lets you make a familiar measurement better. Specialized instruments like a phase noise analyzer unlock an entirely new category of experiments.

And, yes, being able to put cross-correlation phase noise measurements on the résumé doesn’t hurt either.

There is something wonderfully ridiculous about accumulating enough specialized RF instrumentation that the home lab slowly starts resembling a small corporate R&D lab.

The difference is that I don’t have to submit a capital equipment request.

So What Now?

The next step is to start putting the setup to work: comparing synthesizers and reference oscillators, looking at PLL behavior, experimenting with measurement bandwidth and correlation count, and determining just how far down I can push measurements before I genuinely hit the system floor.

I’d also like to use it as another tool for investigating clock quality in high-speed digital and mixed-signal systems, particularly where phase noise starts becoming jitter and jitter starts becoming an actual system-level problem.

So yes, the PN2060D and PNCS-1 are legitimate additions to my RF measurement capabilities.

They are useful engineering tools. They will support actual research. They will help me better understand low-noise RF design.

But I am not going to rewrite history and pretend there wasn’t also a little voice saying:

“That guy on X/Twitter can’t buy one, but I can.”

Sometimes a little urge to one-up a fellow man (especially one who is technically not in EW/RADAR professionally) is a surprisingly effective professional-development strategy.