| 摘要 |
PURPOSE: To unnecessitate a linear amplifier equipped with a variable gain stage by adding a gain control signal to an input signal in a logarithmic domain. CONSTITUTION: In a circuit 80, the set constitution of automatic gain control is simplified by connecting the output of an automatic gain control circuit, that is, an integrator circuit 84 with the logarithmic signal output of an envelope detector 66 by an adding circuit 82. Then, in this circuit, the automatic gain control is operated while a signal is still present in a logarithmic domain. That is, addition in the logarithmic domain is equivalent to multiplication so that the adding circuit 82 can be provided with a gain controlling function. Thus, it is not necessary to provide a variable gain stage after an anti-log device 86. |
