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Automatic Gain Selectable Amplifier

IP.com Disclosure Number: IPCOM000093484D
Original Publication Date: 1967-Oct-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Granata, PJ: AUTHOR

Abstract

Amplifiers 10 and 12, selectively interconnected by switch 14, build up by discrete amounts an input signal from input generator 16. Amplifier 10 can have a relatively high constant gain. Amplifier 12 is a variable gain amplifier. The gain of amplifier 12 is established by selectively switching resistors 18, 20, and 22 into a feedback circuit with that amplifier.

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Automatic Gain Selectable Amplifier

Amplifiers 10 and 12, selectively interconnected by switch 14, build up by discrete amounts an input signal from input generator 16. Amplifier 10 can have a relatively high constant gain. Amplifier 12 is a variable gain amplifier. The gain of amplifier 12 is established by selectively switching resistors 18, 20, and 22 into a feedback circuit with that amplifier.

An operating environment for such an amplifying apparatus is in conjunction with analog-to-digital converter 24. In order to determine how much gain is needed to convert an input signal from generator 16 to optimum input value for ADC 24, a first conversion cycle can be used. During that conversion cycle, switch 14 is opened by a signal on line 26 from control circuitry 28, as is switch 30 by a signal on line 32.

ADC 24 converts the input signal into a digital number. The bits representing that digital number appear in register 42. The higher order bits present in section 44 of register 42 are sensed by decoder circuitry 46 and passed on to circuitry 28 on line 48. Circuitry 28 determines from these higher order bits the magnitude of the input signal supplied from generator 16. According to stored information, circuitry 28 determines the necessary gain for that input signal so as to convert it to an optimum input for ADC 24. Circuitry 28, using that information, then sets the variable gain amplifying apparatus properly for the subsequent true conversion cycle of the in...