US 7,583,943 B2Granted

Automatic gain control device

AssigneeSamsung Electronics Co., Ltd.

InventorTakahiko Kishi

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Abstract

An automatic gain control device capable of reducing signal saturation or signal distortion caused by out-of-band signals of a filter or delay of a control signal. An AGC response control section compares a level of control voltage (‘V2_I terminal’ signal) output from an AGC control section b with a level of control voltage (‘V3_I terminal’ signal) output from an AGC control section c. If the ‘V3_I terminal’ signal is below the ‘V2_I terminal’ signal, an AGC amplifier is controlled by the ‘V3_I terminal’ signal. If the ‘V3_I terminal’ signal is above the ‘V2_I terminal’ signal, the AGC amplifier is controlled by the ‘V2_I terminal’ signal. In the latter case, control information of the AGC control section b is replaced by control information of the AGC control section c so that the AGC control section c controls the AGC amplifier c.

Claims14

Dependent claims

An automatic gain control device comprising:

a first variable gain amplifier for amplifying an input signal;
a filter for limiting a band of an output signal of the first variable gain amplifier;
a second variable gain amplifier for amplifying an output signal of the filter;
a third variable gain amplifier for amplifying and externally outputting the output signal of the filter;
a first control signal generator for generating a first control signal to control a level of the output signal of the first variable gain amplifier to a predetermined level;
a second control signal generator for generating a second control signal to control a level of an output signal of the second variable gain amplifier to a predetermined level and outputting the second control signal to the second variable gain amplifier;
a third control signal generator, with a response characteristic that is faster than that of the second control signal generator, for generating a third control signal for controlling a level of an output signal of the third variable gain amplifier to a predetermined level and outputting the third control signal to the third variable gain amplifier;
a control signal selector for selecting one of the first and second control signals generated from the first and second control signal generators and outputting the selected control signal to the first variable gain amplifier;
and
a reference information copier for copying control information of the second control signal generator into the first control signal generator when the control signal output from the second control signal generator is selected as the control signal for the first variable gain amplifier.

7 more elements

An automatic gain control device comprising:

first variable gain amplifier for amplifying an input signal;
a filter for limiting a band of an output signal from the first variable gain amplifier;
second variable gain amplifier for amplifying and externally outputting an output signal of the filter;
first control signal generator for generating a first control signal to control a level of the output signal of the first variable gain amplifier to a predetermined level;
second control signal generator for generating a second control signal to control a level of an output signal of the second variable gain amplifier to a predetermined level and outputting the second control signal to the second variable gain amplifier;
control signal selector for selecting one of the first and second control signals output from the first and second control signal generators and outputting the selected control signal to the first variable gain amplifier;
and
reference information copier for copying control information of the second control signal generator into the first control signal generator, when the control signal output from the second control signal generator is selected as the control signal for the first variable gain amplifier.

5 more elements

Dependencies are inferred from the claim text.