| 摘要 |
PURPOSE:To improve the frequency characteristic when a signal is attenuated by connecting a gain control AC signal source and a DC signal source in parallel between the emitters of TRs of differential connection and common so as to constitute a gain control circuit. CONSTITUTION:The gain control AC signal source 13 and the DC signal source 14 are connected in parallel between the emitters of the TRs 11, 12 and common respectively and an input signal inputted to bases 17, 18 of the TRs 11, 12 is controlled in response to the value of the signal sources 13, 14 to output a gain-controlled signal from an output terminal 19. A DC current component of the signal source 14 is included in the collector current of the TRs 11, 12 by connecting the DC signal source 14 but no effect is given at all to the AC output voltage obtained at the output terminal 19. Thus, the DC current component is added to increase the operating current of the TRs thereby improving the frequency characteristic of the TRs.
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