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Peak Detector Comparator

IP.com Disclosure Number: IPCOM000082365D
Original Publication Date: 1974-Nov-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Harr, JD: AUTHOR

Abstract

This circuit arrangement comprises an alternative comparator for the peak detector circuit used in bar coding applications.

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Peak Detector Comparator

This circuit arrangement comprises an alternative comparator for the peak detector circuit used in bar coding applications.

A peak detector 100 utilizes operational amplifiers with feedback diodes as voltage-responsive devices. In the detector 100 the input terminal 12 is coupled through a capacitor 42 to a junction terminal 16. The junction terminal 16 is coupled to the negative input terminals of the operational amplifiers 82 and 86, and diodes 84 and 88 are coupled between the negative input terminals and the output terminals of the amplifiers. In the present example, the operational amplifiers 82 and 86 comprise integrated circuits sold under the designation SN52558 by Texas Instruments Company.

Reference voltages are provided by an arrangement which includes a pair of like resistors 104 and 106, and a resistor 108.

Positive operating potential is applied to the positive input terminal of the operational amplifier 82 through the resistor 104. Similarly, a ground connection is connected to the positive input terminal of the operational amplifier 86 through the resistor 106. The resistor 108, which determines the size of the dead zone, is coupled between the positive input terminals of the amplifiers 82 and 86. The resistor 108 can be variable or can be replaced with resistors of other value to change the size of the dead zone, as required.

The output of the operational amplifiers 82 and 86 are coupled to a comparator comprising a third amplifier 220 and five resistors 222, 224, 226, 232 and 234.

The third amplifier 220 is connected to operate as a Schmitt trigger circuit. Posi...