| 摘要 |
<p>PURPOSE:To select an amplifying unit to be operated by selectively supplying a bias current to the base of the differential amplifying transistors(TR) of the plural amplifying units according to a control signal. CONSTITUTION:A bias supply control circuit 7 is provided, and by supplying a base bias to one of amplifying units 1 and 2 according to the control signal, and preventing the supply to the other one, the amplifying unit 1 or 2 is selected. For example, when the control signal is at a high level, a TR Q9 of a bias supply control circuit 7 is turned off, a TR Q8 is turned on, the amplifying unit 1 is operated, and the amplifying unit 2 is disconnected. In such a constitution, an input side and an output side can be used as matrix circuits to treat component signals in plural forms, and thus, a preferable signal amplifying circuit can be obtained.</p> |
