Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

High Frequency Measuring System

IP.com Disclosure Number: IPCOM000093929D
Original Publication Date: 1966-Apr-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 32K

Publishing Venue

IBM

Related People

Bertin, CL: AUTHOR

Abstract

In this high-frequency measuring system the voltage across and the current through an unknown load are measured. The test readings are taken at a point remote from the load. In making measurements within microcircuit complexes, the physical difficulty of attaching the instruments close to the load requires that coaxial transmission lines be used.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

High Frequency Measuring System

In this high-frequency measuring system the voltage across and the current through an unknown load are measured. The test readings are taken at a point remote from the load. In making measurements within microcircuit complexes, the physical difficulty of attaching the instruments close to the load requires that coaxial transmission lines be used.

The impedance being measured is contained within unit under test 10 and is connected to an AC voltage source 12 via resistor 14 and coaxial transmission line 16. The electrical length of line 16 is indicated as t. The value of resistor 14 is conveniently made equal to the characteristic impedance, i.e., resistance Ro, of line 16. Open circuited transmission line 18 and short-circuited transmission line 20 are connected via resistors 22 and 24 to source 12. Measurement points 1, 2, and 3 are located at a measuring device such as an oscilloscope or sampling oscilloscope for display and measurement purposes not shown.

To determine the potential Vu across unit 10 the output of source 12 is applied via resistor 14 and line 16 to unit 10. For a time 2t, the potential at point 1 is unaffected by unit 10. This is because it takes this long for the waveform to travel up to and return from unit 10. To eliminate this portion of the waveform, which contains no valid measurement information from zero time to 2t, the identical test pulse is applied to transmission line 20 via resistor 24. The potential at point 3 is identical to that at point 1 for the duration 2t, transmission line 20 being shorted at its far end. By subtracting these potentials from each other, the initial portion of the measurement waveform is eliminated and an accurate measure of potential Vu at unit 10 is achieved.

Current Iu into unit 10 cannot be determined simply by taking the potential drop across resistor 14. This is due to the fact that the connection of line 16 into the circuit allows the inherent parallel cap...