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Signal Jitter Measurement with Electron-Beam Prober

IP.com Disclosure Number: IPCOM000116276D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Jenkins, KA: AUTHOR

Abstract

Electron-beam probing can be used to measure internal circuit waveforms with high bandwidth. However, since it is a sampling method, there is no way to measure the time jitter of the waveforms. In sampling measurements, timing jitter is averaged, and appears only in the signal transition time, where it is indistinguishable from true signal transition time. It can be very important in design verification of VLSI circuits, where jitter - or clock skew - of internal signals can lead to malfunction.

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Signal Jitter Measurement with Electron-Beam Prober

      Electron-beam probing can be used to measure internal circuit
waveforms with high bandwidth.  However, since it is a sampling
method, there is no way to measure the time jitter of the waveforms.
In sampling measurements, timing jitter is averaged, and appears only
in the signal transition time, where it is indistinguishable from
true signal transition time.  It can be very important in design
verification of VLSI circuits, where jitter - or clock skew - of
internal signals can lead to malfunction.

      While jitter measurements have been made possible in sampling
oscilloscopes, no such technique exists for electron-beam
measurements of waveforms.

      Disclosed is a circuit and method for measuring waveform timing
jitter with an electron-beam prober.  The principle of jitter
measurement is described in Figs. 1A and 1B.  A waveform is measured
with the conventional waveform feature of the e-beam prober.  Voltage
cursors, V+ and V-, are placed on the trace, and serve to define a
window for jitter measurement.  For waveforms whose voltage is within
these limits, the arrival time of the waveform is measured, and a
histogram of this arrival time made.  This histogram measures the
jitter of the waveform.

      While this has the appearance of the histogram feature of
conventional electrical oscilloscopes, its implementation in an
e-beam probing system requires a special circuit.  This circuit is
shown in Fig. 2.

      The new features of the jitter measuring circuit are enclosed
in the box.  The secondary electron signals from the circuit are
amplified by a photomultiplier tube (PM).  The timing generator
directs the timing of...