| 摘要 |
PURPOSE:To extend the dynamic range, by applying a current offset to a control voltage generating circuit and reducing the base voltage fluctuation of a transistor (TR) constituting a current gain control circuit. CONSTITUTION:Bases of TRsQ'1, Q''1 are connected in common to an input terminal I1. Bases of TRsQ'2 and Q''2 are connected in common to the other input terminal I2. Emitters are connected to constant current sources I01, I02. Collectors of the TRsQ''1, Q''2 are connected to the current gain control circuit. When the potential of the input terminal I2 is high and the TRsQ'2 and Q''2 turn on, the TRsQ'2, Q''2 are switched off with an input control voltage VC increased, the timing when the TRQ''1 turns on is delayed than that when the TRsQ'2, Q''2 turn off. This means that the fluctuation of the base voltage of TRs constituting the current gain control circuit becomes less. |
