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Accurately Observing the Signals from Repetitive, Triggerable Sources in the Low Microvolt, Low Picosecond Range

IP.com Disclosure Number: IPCOM000084723D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Elliott, BJ: AUTHOR

Abstract

In certain areas of scientific research, for example in the study of Josephson junction switching, it is necessary to be able to accurately determine the waveforms of small (less than 2 mV), very fast (rise time 50 psec or less) electrical transients. Commercial viewing systems have neither the necessary low-noise level nor the time position stability that is needed to meet the demands of this measurement problem.

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Accurately Observing the Signals from Repetitive, Triggerable Sources in the Low Microvolt, Low Picosecond Range

In certain areas of scientific research, for example in the study of Josephson junction switching, it is necessary to be able to accurately determine the waveforms of small (less than 2 mV), very fast (rise time 50 psec or less) electrical transients. Commercial viewing systems have neither the necessary low-noise level nor the time position stability that is needed to meet the demands of this measurement problem.

When the small signals to be viewed are repetitive and are generated from a triggerable source (as with Josephson junctions) then it is possible, using the method described herein, to observe signals that are much smaller than those which can be seen with conventional sampling oscilloscopes (such as a Hewlett- Packard 1430A and supporting equipment).

Described is a measurement technique for picosecond pulses having amplitudes below that of the noise level of the sampling oscilloscope. The technique is an extension of earlier known methods referred to above. A combination of analog-digital signal averaging (to smooth the incoherent noise), signal sampling (to achieve sufficient time resolution), and the use of special triggering and control circuits (to circumvent the long-term, position drift problem and therefore allow signal smoothing without waveform distortion) is utilized in the method.

In the present method, the low noise, relatively la...