Browse Prior Art Database

Zero Crossing Detector

IP.com Disclosure Number: IPCOM000083564D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Braquet, H: AUTHOR [+3]

Abstract

Shown is a logic circuit allowing the positive zero crossings and negative zero crossings of a periodic wave to be detected The detector comprises two threshold circuits 2 and 3. Circuit 2 is a trigger which is set by a rising signal having a first level A, and which is reset by a decreasing signal having a second level B. Circuit 3 is a comparator and provides an uplevel pulse when its input signal is at a level C.

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Zero Crossing Detector

Shown is a logic circuit allowing the positive zero crossings and negative zero crossings of a periodic wave to be detected The detector comprises two threshold circuits 2 and 3. Circuit 2 is a trigger which is set by a rising signal having a first level A, and which is reset by a decreasing signal having a second level B. Circuit 3 is a comparator and provides an uplevel pulse when its input signal is at a level C.

The logic arrangement of inverters I4 and I5 and of AND circuits A6 and A7 provides on outputs 8 and 9, pulses which are indicative of the zero crossings of the input periodic wave applied on input 1. Periodic wave a shown on the drawing is fed to circuits 2 and 3. Circuit 2 provides to circuit A6 and to inverter I4 signal b. Circuit 3 provides to AND circuit A7 and to inverter I5 signal c.

AND circuit 6 performs the logic operation b.c and its output d on 8 is indicative of the negative zero crossings of the periodic wave applied on input 1. AND circuit 7 performs the logic operation c.b and its output e on 9 is indicative of the positive zero crossings of the periodic wave applied on input 1.

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