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Jitter Measurement Method

IP.com Disclosure Number: IPCOM000075471D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Tolley, JH: AUTHOR

Abstract

A pulse whose jitter is to be measured is fed to input A of a dual-trace oscilloscope 10 through a T-pad 12 and displayed on the face of oscilloscope 10 at image a, as indicated in Figs. 1, 2, 3 and 4. This pulse is also fed to input B through T-pad 12 and a calibrated adjustable trombone delay line 14, and displayed on the face of oscilloscope 10 at image b to the left of image a in Figs. 1 and 2. Delay line 14 is adjusted so that edge 16 of image a and edge 18 of image b coincide in such a manner that no dark edge is seen at their junction. Since the display is expected to follow a Gaussian distribution, sample population is lower near the edges of the images. Overlapping the edges until the distribution is uniform across the two images permits the approximate root-mean-square (RMS) value to be obtained.

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Jitter Measurement Method

A pulse whose jitter is to be measured is fed to input A of a dual-trace oscilloscope 10 through a T-pad 12 and displayed on the face of oscilloscope 10 at image a, as indicated in Figs. 1, 2, 3 and 4. This pulse is also fed to input B through T-pad 12 and a calibrated adjustable trombone delay line 14, and displayed on the face of oscilloscope 10 at image b to the left of image a in Figs. 1 and 2. Delay line 14 is adjusted so that edge 16 of image a and edge 18 of image b coincide in such a manner that no dark edge is seen at their junction. Since the display is expected to follow a Gaussian distribution, sample population is lower near the edges of the images. Overlapping the edges until the distribution is uniform across the two images permits the approximate root-mean- square (RMS) value to be obtained. When the point of uniformity is obtained, as indicated in Fig. 2, a reading Tba, for example in picoseconds, on delay line 14 is noted. Thereafter, delay line 14 is again adjusted so that image b is on the right side of image a, as indicated in Figs. 3 and 4. Delay line 14 is now adjusted so that edge 20 of image a and edge 22 of image b coincide in such a manner that no dark edge is seen at their junction, and a reading Tab on delay line 14 is again noted. The RMS pulse jitter is defined as T(jRMS) = Tab - Tba over 2 picoseconds.

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