Système de mesure d'impulsions électriques

摘要

1, 021, 240. Measuring short time intervals; testing semi-conductor diodes. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 22, 1965 [Jan. 23. 1964], No. 2851/65. Heading G1U. In an arrangement for obtaining a measure of when a cyclically recurring pulse reaches a predetermined amplitude the pulse is sampled and a servo system adjusts the sampling time so that it is stabilised at the instant at which the predetermined magnitude is obtained. The system is applied to measuring the reverse recovery time of a semi-conductor diode 11, fig. 1. Pulses applied from generator 14, produce a reverse current in the diode 11 and thus develop and output pulse across resistor 13. This output pulse is sampled by gate 17, and the resulting gate output modifies the charge on a capacitor in the level hold unit 18, producing an output which is fed via amplifier 19 to unit 45 which controls the time at which the sample is taken. Initially switch 21 is set to contact 22a, connecting a reference source 261, and switches 29, 34 are set to connect amplifier 31 into circuit. The system then stabilizes to a point on the leading edge of the diode reverse current pulse C, Fig. 2 (not shown) at which the pulse amplitude is equal and opposite to the reference voltage e 26 1. The resulting output from level hold unit 18 is fed round the system to amplifier 48 to produce a reference output e 0 which is adjustable by means of source e' R , and which corresponds to a reference time. To measure the time interval between this reference time and the time at which the trailing edge of the diode reverse current falls to some desire value switches 21, 29, 34 are set to their other positions, and voltage e R is adjusted to correspond to the desired value at which measurement is to be made. The system will now stabilize to a new point, giving a different output e 0 , the difference between this output and the original one being a measure of the pulse width at the desired value. By varying e R , a plot of the pulse width at different amplitudes may be obtained.