| 摘要 |
PURPOSE:To switch output signals by a receiver without using any changeover switch by using an opposite-polarity transistor(TR) which is applied with a proper current feedback type bias as a load on the TR of one signal output circuit. CONSTITUTION:An amplifier on an optional signal side is selected by a switch 3 between amplifiers 1 and 2. When the amplifier 2 is selected with a signal input B, a signal is supplied to a buffer amplifier composed of a bias resistance 6, an amplification setting resistance 8, and a TR 7 through a capacitor 5. The amplifier 1, on the other hand, is selected with a signal input A and the signal appears at an output terminal through a capacitor 4. The collectors of TRs 7 and 11 are connected through a capacitor 12 as the load on the amplifier 1, but the base sides of the TRs 7 and 10 are fixed in terms of AC, so extremely high impedance is obtained and its influence is a little. Consequently, the signal inputs A and B can be switched with the switch 3.
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