Patent ID: 6326842
Filing Date: 2001-12-04
Classification: H03F,H03G

Abstract:
A variable gain amplifying apparatus comprising:a first amplifying circuit having a first variable gain when the first amplifying circuit is activated;a second amplifying circuit having a second gain and having an input which is connected to an output of the first amplifying circuit;a third amplifying circuit having a third gain when the third amplifying circuit is activated and having an input which is connected to an output of the second amplifying circuit, wherein said first, second and third amplifying circuits are connected in series; anda gain controller generating gain control signals which are applied to the first and third amplifying circuits such that the first and third gains are set to predetermined gains, respectively;wherein the second gain is a fixed gain;the first amplifying circuit comprises a plurality of first amplifiers which are activitated to set the first variable gain based on the gain control signal;the second amplifying circuit has a single second amplifier; andthe third amplifying circuit comprises a plurality of third amplifiers which are activated to set the third variable gain based on the gain control signal.