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Modified Recirculating Technique

IP.com Disclosure Number: IPCOM000091323D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Merrill, JF: AUTHOR

Abstract

This recirculating tester, for measuring either turnon or turnoff time of devices, eliminates the need for an external source of test pulses. The tester requires a start pulse to initiate the oscillations. The circuit comprises one-shot multivibrator 1 which is interposed between delay network 2 and the input of a circuit unit under test 3. The closed-loop circuit thus formed, functions as an oscillator, the frequency of which is a function of the inherent characteristics of unit 3. Normally, one-shot 1 recovers in less time than the delay of delay 2. Counter 4 can be used to determine a highly accurate frequency with, e.g., picosecond accuracy.

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Modified Recirculating Technique

This recirculating tester, for measuring either turnon or turnoff time of devices, eliminates the need for an external source of test pulses. The tester requires a start pulse to initiate the oscillations. The circuit comprises one-shot multivibrator 1 which is interposed between delay network 2 and the input of a circuit unit under test 3. The closed-loop circuit thus formed, functions as an oscillator, the frequency of which is a function of the inherent characteristics of unit 3. Normally, one-shot 1 recovers in less time than the delay of delay 2. Counter 4 can be used to determine a highly accurate frequency with, e.g., picosecond accuracy.

For example, to measure t(on) of a circuit, such an arrangement generates an output pulse for each input pulse. By such interpositioning of one-shot 1, its frequency of oscillation is only dependent on the turnon delay of unit 3, delay of the feedback network, and the delay of one-shot 1 if its pulse width is less than the delay of the feedback network. Because the feedback delay and the delay of one-shot 1 are known constants, the turnon characteristics of unit 3 can be determined to provide a more accurate characterization of such unit..

The period of recirculation is P(rec)=t(x) + t(d) +t(ss) where t(x)= turn-on. characteristic of unit 3, t(d)= delay, a constant, of delay 2, and t(ss)= delay of one-shot 1, a constant. Thus f(rec) = 1/(t(x) + t(d) + t(ss)). If the input pulse is used to...