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Differential Amplifier With Limiter

IP.com Disclosure Number: IPCOM000073795D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Betts, A: AUTHOR [+3]

Abstract

Differential limiting by utilizing two side-by-side diodes 10 and 12 is employed in the integrated circuit differential sense amplifier.

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Differential Amplifier With Limiter

Differential limiting by utilizing two side-by-side diodes 10 and 12 is employed in the integrated circuit differential sense amplifier.

Matched transistors 14 and 16 have input resistors 18 and 20 connected to the bases thereof. Differential input signals are applied at input terminals 22 and 24 to the bases of the transistors 14 and 16. When a large positive signal is applied to terminal 22 the current through transistor 14 increases until substantially all of the current passing through sink resistor 26 flows through transistor 14, and diode 10 is turned on. With diode 10 conducting, each of load resistors 28 and 30, which are of equal value, carry about one half of the total current flowing through transistor 14. Since there is only a slight increase in current passing through load resistor 28, depending upon the characteristics of diode 10, there is only a relatively small change in voltage at output terminal 32 due to the large input signal applied to input terminal 22.

When a large positive signal is applied to input terminal 24, diode 12 conducts to stabilize the voltage at output terminal 34, in a similar manner. When small signals are applied to the input terminals 22 and 24, the diodes 10 and 12 are in a nonconduction condition and normal amplification of these signals is produced.

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