Variable gain amplifier
AssigneeKabushiki Kaisha Toshiba
InventorsTakashi Ueno, Tadashi Arai, Tetsuro Itakura
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Abstract
A variable gain amplifier device comprises a variable gain amplifier circuit which amplifies a difference between an input signal and a feedback signal to output an output signal, a feedback circuit which supplies the feedback signal to the variable gain amplifier circuit, and a controller which controls the variable gain amplifier circuit and the feedback circuit to decrease a cutoff frequency of the feedback circuit according to increase of a gain of the variable gain amplifier circuit or vice versa.
Claims13
A variable gain amplifying method comprising:
- supplying to a variable gain amplifier an input signal and a feedback signal from a feedback circuit to amplify a difference between the input signal and the feedback signal;
- and
- decreasing a cutoff frequency of the feedback circuit with an increase in a gain of the variable gain amplifier circuit or vice versa.
A variable gain amplifying method comprising:
- supplying to a variable gain amplifier circuit an input signal and a feedback signal from a feedback circuit to amplify a difference between the input signal and the feedback signal;
- and
- controlling the gain of the variable gain amplifier circuit and a cutoff frequency of the feedback circuit to make a lower limit frequency of the output signal substantially constant regardless of variation of a gain of the variable gain amplifier circuit.
A variable gain amplifying method comprising:
- supplying to a variable gain amplifier circuit an input signal and a feedback signal from a feedback circuit to amplify a difference between the input signal and the feedback signal, a gain of the variable gain amplifier circuit being varied according to a level of at least one of the output signal and the input signal;
- and
- varying a cutoff frequency of the feed back circuit according to a variation of the gain of the variable gain amplifier circuit to make a lower limit frequency of the output signal substantially constant.
Dependencies are inferred from the claim text.