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Switch Time Measurement for Magnetic Elements

IP.com Disclosure Number: IPCOM000091664D
Original Publication Date: 1968-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Fritz, HE: AUTHOR

Abstract

In this circuit arrangement, a ramp generator is controlled by a single pulse to determine the switching time characteristics of a magnetic element. The pulse response generated by switching of the state of a magnetic element is a relatively short pulse of one to ten nanoseconds which does not lend itself to any simple manner of measuring to determine the switching time. The pulse response or switching time characteristic is indirectly measured by measuring Ts. This is the interval between a predetermined time To and a preselected point on the pulse response curve. This is accomplished by initiating at time To the charging of a capacitor through a constant current source.

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Switch Time Measurement for Magnetic Elements

In this circuit arrangement, a ramp generator is controlled by a single pulse to determine the switching time characteristics of a magnetic element. The pulse response generated by switching of the state of a magnetic element is a relatively short pulse of one to ten nanoseconds which does not lend itself to any simple manner of measuring to determine the switching time. The pulse response or switching time characteristic is indirectly measured by measuring Ts. This is the interval between a predetermined time To and a preselected point on the pulse response curve. This is accomplished by initiating at time To the charging of a capacitor through a constant current source. If the decay of the response pulse reaches the preselected point within a predetermined maximum time, the capacitor is discharged, and no output is produced, representing an accept condition of the magnetic element being tested. If the pulse does not decay to the selected point within the required time, a reject command is generated.

The circuitry is conditioned by a gate pulse which enables gate 12 and removes the clamping diode from pulse amplifier 14. A time synchronization pulse at time To is applied to amplifier 14 which fires the tunnel diode switched emitter-follower 16. The output from emitter-follower 16 is connected to ramp start amplifier 18. The leading edge of the negative-going output pulse from amplifier 18 occurs at time To. This pulse is applied to analog voltage converter
20. The latter consists essentially of a capacitor which starts to charge linearly through constant current source 22....