| 摘要 |
<p>The circuit has an accurately defined operating frequency controlled by dual resonators. The tunable passband filter is situated at the input of a radio receiver. It comprises two resonators (10). Each of these resonators has an input node (11) and comprises, between its input node and earth, a parallel assembly of a resonant element with a transmission line (12) and at least one variable capacitor (13) controlled by a tuning voltage (Vacc). A capacitive coupling (23,24) is provided between an input (21) of the filter and the input node of one of the resonators, and also between the input node (11) of the other resonator and an output (22) of the filter. The coupling between the resonators (10) is completed by an inductance (20) connected between their input nodes.</p> |
