| 摘要 |
PURPOSE:To widen a frequency characteristic of an unbalance/balance converter, to reduce the gain, and also to improve the output balance degree by connecting in cascade a differential amplifier to which a voltage feedback has been applied, to an output of a differential amplifier to which an emitter current feedback has been applied. CONSTITUTION:The first differential amplifier A consists of transistors (TR) 1, 2 and 7, and resistances 21, 22, 25, 26 and 31. The second differential amplifier B consists of TRs 3, 4 and 8, and resistances 27, 28 and 32, and a voltage feedback is applied from the respective collectors of the TRs 3, 4 to the bases by TRs 29, 30 and resistances 29, 30. As a result, since the resistance is not connected in series to emitters of the TRs 3, 4, even if there is a considerable unbalance in an input balance signal, a balance property of an output signal is improved remarkably. Also, a time constant which is determined by a collector load resistance of the amplifier A and its collector capacity becomes small, and a frequency characteristic of the amplifier A is improved.
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