asured clock, with a gain of 100mV per nanosecond of jitter. The instrument's measurement bandwidth is 500Hz-100kHz, and the intrinsic (residual) jitter is less than 30ps. This 30ps figure defines the minimum jitter level that can be measured by the instrument. Figs.8 and 9 show the instrument's bandwidth and intrinsic jitter, respectively. The plots of fig.9, made with different input signals to the analyzer, represent the combined performance of the test transport and analyzer. Although the spectral analysis in fig.9 is extended to 200kHz, the jitter numbers in the caption represent the RMS jitter values calculated over a DC-40kHz bandwidth.
Fig.7 UltraAnalog jitter analyzer architecture.
Fig.8 UltraAnalog jitter analyzer frequency response.
Fig.9 UltraAnalog jitter analyzer, spectrum of intrinsic jitter (19.3ps, solid line); while decoding 1kHz at 0dBFS (27.8ps, long-dashed line); decoding 1kHz at -60dBFS (32.1ps, short-dashed line); and decoding 60Hz+7kHz in a 4:1 mix at 0dBFS (29.1ps, dotted line) (vertical scale is ps per 1/3-octave band).
With this jitter-analysis instrument, we can measure and quantify the performance of any digital source and interface combination, such as CD transports, DAT machines, or "jitter-reduction" devices. In addition, the analyzer can measure the performance of a digital processor's input receiver circuitry.
Footnote 7: The way in which a 4kHz signal can produce a 100Hz line by beating with 44.1kHz can be explained by the fact that the data-to-jitter crosstalk is highly nonlinear, and that all harmonics of the 4kHz frequency, including 44.0kHz, are present and beat with 44.1kHz.—Rémy Fourré