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Adaptive Automatic Gain Control Amplifier

IP.com Disclosure Number: IPCOM000060329D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Einkauf, MA: AUTHOR

Abstract

A method is described to provide a way for a single Automatic Gain Control (AGC) amplifier to be used for signals whose expected minimum magnitudes vary. An AGC amplifier is used to amplify signals of varying magnitudes so that the resulting output is of uniform magnitude. The AGC has a finite maximum allowable gain which sets the lower limit for an input signal magnitude for which the output of the AGC will be of uniform magnitude. If a signal is below this lower limit, it will be amplified, but since the gain has an upper limit, the output will not be as large as the output due to a signal above this lower limit. The value of the AGC maximum gain establishes the lower limit on the input magnitude.

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Adaptive Automatic Gain Control Amplifier

A method is described to provide a way for a single Automatic Gain Control (AGC) amplifier to be used for signals whose expected minimum magnitudes vary. An AGC amplifier is used to amplify signals of varying magnitudes so that the resulting output is of uniform magnitude. The AGC has a finite maximum allowable gain which sets the lower limit for an input signal magnitude for which the output of the AGC will be of uniform magnitude. If a signal is below this lower limit, it will be amplified, but since the gain has an upper limit, the output will not be as large as the output due to a signal above this lower limit. The value of the AGC maximum gain establishes the lower limit on the input magnitude. In many digital signal processing applications it may be necessary to change the lower magnitude limit to which the AGC fully responds. For example, if the system employing the AGC expects signals of two different magnitudes, it may be necessary to increase or decrease the sensitivity, depending on whether the input has a high or low magnitude. This is accomplished by changing the maximum allowable gain of the AGC. In this way, the system can use the same AGC with only slight modifications for several signals of varying magnitudes. Although it is possible to always have the AGC maximum gain set at the value necessary for the smallest expected signal, it may not always be desired. For example, if the system expects signals of 1...