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Amplifier + Automatic Gain Control

IP.com Disclosure Number: IPCOM000096621D
Original Publication Date: 1963-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Funk, HL: AUTHOR

Abstract

The single stage amplifier with automatic gain control consists of transistors 10 and 18. Their emitters are connected through a common line 20 to the collector of transistor 22. The emitter of 22 is connected through resistor 24 to negative potential source 26. The collector of 10 is connected directly to positive potential source 28. The collector of 18 is connected to 28 through load resistor 30. The collector of 18 also connects to output terminal 32 and through rectifier 34 and integrator 36 to the base of 22.

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Amplifier + Automatic Gain Control

The single stage amplifier with automatic gain control consists of transistors 10 and 18. Their emitters are connected through a common line 20 to the collector of transistor 22. The emitter of 22 is connected through resistor 24 to negative potential source 26. The collector of 10 is connected directly to positive potential source 28. The collector of 18 is connected to 28 through load resistor
30. The collector of 18 also connects to output terminal 32 and through rectifier 34 and integrator 36 to the base of 22.

The current drawn by the amplifier is controlled by the bias potential applied to the base of 22. In operation, the base of 18 is connected to ground and an input signal is applied to the base of 10 through input terminal 14. The output signal on output line 38 follows the input signal on 14.

The negative half cycles of the output signal are applied through 34 to 36. When the average amplitude of these negative half cycles increases, the DC potential level applied by 36 to the base of 22 reduces the conduction of 22. Thus, less emitter current is applied to 10 and 18 which produces a reduction in gain. This reduction counteracts the increase in the amplitude of the input signal. It restores the average amplitude of the output signal applied to line 38 to the desired amplitude level.

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