| 摘要 |
PROBLEM TO BE SOLVED: To provide the trap circuit of low insertion loss and sharp rejection characteristics by making a parallel capacitance variable, constituting it by a variable capacitive diode and constituting a resistor by a control dynamic resistance element. SOLUTION: The parallel capacitance Cp is constituted of the variable capacitive diodes D1 and D2 and a fixed capacitor 6 serially arrayed in an inverse conducting direction. Also, a variable resistor RR is constituted of a PIN diode provided with the characteristics of variable dynamic resistance when a flowing DC current is changed for instance as the control dynamic resistance element. By the constitution, since the parallel capacitance Cp becomes freely controllable and the dynamic resistance of the resistor RR also becomes freely controllable, just by affecting only the resistor RR and the parallel capacitance Cp, a frequency is adjusted within a prescribed range while keeping performance. Also, rejection is sharpened and the resistance value of the variable resistor RR is lowered and made suitable.
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