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E-Beam Measurements of DC Voltages by Pseudo-Waveform Method

IP.com Disclosure Number: IPCOM000036723D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 120K

Publishing Venue

IBM

Related People

Jenkins, KA: AUTHOR

Abstract

A technique is described whereby an electron (E)-beam tester can be used to make measurements of DC voltages on circuit lines. This is achieved by a simple modification of the waveform-measurement method.

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E-Beam Measurements of DC Voltages by Pseudo-Waveform Method

A technique is described whereby an electron (E)-beam tester can be used to make measurements of DC voltages on circuit lines. This is achieved by a simple modification of the waveform-measurement method.

Electron beam testers are widely used in circuit testing to measure voltages on circuit lines. However, the voltages to be measured must be changing, typically at 1 KHz or above, in order for the measurement apparatus to function. Thus, the measurements are known as waveform measurements, and only voltage changes are measured. If the tester is used to measure a line having a static voltage, a waveform consisting of a straight line will result, but its absolute value will be unknown. There are cases when a DC voltage measurement is needed. The concept described herein makes it possible to use an E-beam tester to measure static voltages. The mechanism of waveform measurement is used, but instead of changing the time delay of the electron beam to generate the waveform, its position is varied.

The method of conventional E-beam testing is to maintain a constant current through a spectrometer filter grid. The grid bias is adjusted via a feedback loop to maintain a constant current level. A change in the specimen voltage results, via this mechanism, in a change in the filter grid voltage. This voltage is then equivalent to a waveform.

As far as the operation of this system is concerned, the tester only requires that the primary beam strike a circuit element whose voltage is changing above a minimum rate. In the intended application, the primary beam strikes a single line which has a changing voltage. In the method described here, the beam, instead, is moved across the circuit lines at a fast enough rate to satisfy the minimum tester rate. Thus,...