| 摘要 |
PURPOSE:To obtain the limiter circuit which is variable in limiter level by providing a control circuit which controls the operating current of a differential amplifying circuit according to a control signal. CONSTITUTION:A current IL flows to a resistance 17 corresponding to the control signal applied to the base of a transistor(TR) 16 of a control circuit 15. When the mirror ratio of TRs 22 and 43 is set to 1:4, a current 4IL is generated at the collector of the TR 43. When TRs 11 and 13 turn ON corresponding to an input signal, currents 2IL flow to the collectors of the TRs 11 and 13 by the collector current 4IL of the TR 43 and a current 2IL is generated at the collector of a TR 30 through a current mirror circuit 31. When the TRs 11 and 13 turn OFF and TRs 12 and 14 turn ON, on the other hand, the collector current of a TR 36 becomes 2IL. The current IL varies with a control voltage, so the limiter level can be varied. |
