Instrument tests clock circuits, PLLs, oscillators

Wavecrest is rolling out a family of instruments dubbed signal source analyzers (SSAs) for testing clock circuits, phase locked loops (PLLs) and oscillators.

Historically, three to four instruments—such as spectrum analyzers, phase-noise analyzers, jitter analyzers, and oscilloscopes—would have been necessary to cover the test specs required for today's clock devices. Since each of these instruments uses different methodologies for their individual measurements, and each uses a unique terminology, it's virtually impossible to correlate results.

Frequency, amplitude, time
With the advent of Wavecrest's SSAs, one instrument can measure in three domains: frequency, amplitude and time. Nonetheless, the SSAs use industry-familiar terminology and visually recognizable plots, so that you can readily understand and interpret all results. An SSA can also translate results from any one of the three domains to the other, making it the Rosetta Stone of oscillator analysis instruments.

Wavecrest President and CEO Dennis Leisz contends their SSA-20 and SSA-50 analyzers will save thousands of dollars in multiple product investment costs. "They offer features that go beyond those of the traditional analysis devices, in just one instrument," he said.

"These triple-domain analyzers provide the greatest range of functionality compared to any single domain analyzer, including phase-noise analysis, transfer function analysis, jitter measurements, and timing measurements—plus 15GHz oscilloscope capability."

Low noise-floor
With noise-floor specifications less than -160dBc/Hz (at 10kHz), Leisz contends Wavecrest's SSAs offer superior resolution and bandwidth compared to phase-noise analyzers in a similar price class. That can let you more quickly identify out-of-phase crosstalk riding on a signal.

In use, an SSA instrument provides direct measurement of output skew and jitter, R_J (random jitter) and T_J (total jitter), as well as displaying the jitter spectrum. The SSA measures amplitude noise and separates it into its components (R_N [random noise] and D_N [deterministic noise]) to give a T_N (total noise) value. The jitter spectrum is measured from 0.04Hz to the Nyquist (fc/2) of the clock.

Direct measurement of transfer function
Other first-to-market features include direct measurement of transfer function so you can do sophisticated second-order and third-order PLL and DLL tests. The system's suite of tools can verify if a prototype meets design simulation criteria, as well as provide a one-glance view of the entire spectrum from the lowest frequency to Nyquist (fc/2).

Wavecrest's new SSAa are priced starting at about $60,750.

- Alex Mendelsohn
eeProductCenter