| 摘要 |
<p>An input trap circuit (10) removes a predetermined frequency component included in an input signal and then outputs the input signal to a circuit at a later stage. The input trap circuit is provided with: a parallel oscillation circuit (L1, D2, D3) in which a pair of variable capacitance diodes are connected in serial such that cathodes thereof are connected to each other at a junction portion (J1) and in which an inductance is connected in parallel to the variable capacitance diodes between anodes of the variable capacitance diodes at both ends thereof; a voltage applying device (R1) for applying a voltage to the junction portion so as to vary capacitance values of the variable capacitance diodes on the basis of reverse voltage characteristics of the variable capacitance diodes respectively; and a variable capacitor element (CT1) connected between the junction portion and a ground. <IMAGE></p> |
