| 摘要 |
PURPOSE:To avoid the occurrence of reflection for the signal between the interfaces, by constituting that the input impedance is made constant at all times for either of normality or squerch of the transistor base common amplifying circuit having the squerch function. CONSTITUTION:The collector of the transistor 11 of common base is grounded via the switch 16. The input terminal 14 of the base common amplifying circuit is grounded with the varactor diode 31 va the DC blocking capacitor 31. The cathode of the diode 31 is connected to the output circuit 15 of the switch 16 via the resistor 35 and the high frequency choke 36. Further, the diode 33 is in forward direction with the transistor 11 in DC manner. Thus, when the switch 16 is disconnected, the diode 33 is turned on, which is parallelly connected to the input resistor of the transistor 11, enabling to keep the entire input impedance constant regardless of turning on or off of the switch 16. |
