GB1228345A - - Google Patents

Abstract

1,228,345. Pulse shaping circuits. C.I.T. COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS. 28 Jan., 1969 [29 Jan., 1968], No. 4611/69. Heading H3T. In a circuit for reducing the rise or fall time of an input pulse, the pulse is fed to a first differentiator C 1 , R 2 arranged to provide approximate differentiation of part of the input pulse amplitude and a second differentiator C 1 , Q 2 arranged to provide a more accurate differentiation of a further part of the input pulse. The output of the second differentiator Q 2 is fed to a circuit II which provides an output only when the combination of the input pulse and the output of the second differentiator exceeds a theshold value. As described, input pulses J or J<SP>1</SP> are fed to terminal E which is coupled to a bi-stable circuit Q 3 , Q 4 arranged to energize a relay W when the input pulse J reaches a predetermined threshold. The pulse J is also passed via an emitter follower Q 1 to a differentiating circuit comprising a capacitor C 1 , resistor R 2 and a common-base transistor Q 2 which provides an output when the differentiated trailing edge of the input pulse J reaches a predetermined threshold. This pulse is passed via diode D 1 to the base of transistor Q 3 so as to restore the state of the bi-stable circuit Q 3 , Q 4 and release relay W when the rate of change of the trailing edge has reached a predetermined value. The duration of the output pulse h is substantially independent of the amplitude of input pulses J, J<SP>1</SP>. Q 3 is arranged to operate out of saturation.