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Variable Hysteresis Amplifier Shaper

IP.com Disclosure Number: IPCOM000093184D
Original Publication Date: 1967-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Chew, FB: AUTHOR

Abstract

This circuit provides a squared output in response to positive and negative input signal variations. It has a hysteresis or threshold characteristic for both input polarities that can be varied as needed for noise rejection.

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Variable Hysteresis Amplifier Shaper

This circuit provides a squared output in response to positive and negative input signal variations. It has a hysteresis or threshold characteristic for both input polarities that can be varied as needed for noise rejection.

The input signal is applied across terminals 10 and 11, respectively coupled to the bases of transistor switches T1 and T2. The latter are connected in current switching configuration with their emitters connected in common to transistor T3. This acts as a constant current source and the current it supplies is controlled by potentiometer 13. An input signal of either polarity tends to drive T1 or T2 into conduction and tends to turn the other off. The switch which is driven toward nonconduction experiences a positive voltage excursion at its collector. When this excursion reaches a level sufficient to forward bias diode 14 or 15 connected to the collector of that transistor, one transistor T4 or T5 is caused to conduct. T4 and T5 are connected in a latching arrangement. Thus an input to either one causes the latch to toggle and produces a step change in the output at terminal
16. The output signal at 16 is, thus, a square wave which follows the input signal.

This circuit has the advantage that the threshold or hysteresis characteristics of the circuit can be varied by adjusting potentiometer 13. The latter controls the current in T3 and, consequently, the current through T1 and T2. By controlling the curre...