| 摘要 |
A base band circuit forms a part of an automatic gain controller incorporated in a direct conversion receiver, and includes a series of variable gain amplifiers controlled by a gain controller and a feedback loop connected between the output node and the input node of the series of variable gain amplifiers, wherein the feedback loop has an attenuation circuit connected between the output node of the series of variable gain amplifiers and an inverted integrating circuit which, in turn, is connected through an adder and a low pass filter to the input node of the series of variable gain amplifiers so that direct current offset voltage is eliminated from the output signal of the series of variable gain amplifiers without change of cut-off frequency. |
