| 摘要 |
PURPOSE:To change the frequency band width without deteriorating the amplitude characteristics within a pass band by using a voltage control variable capacity diode having the same characteristics as a band width varying means. CONSTITUTION:The variable capacity diodes 11-14 have the same characteristics and therefore it can be regarded that the capacity double as much as that of the variable capacity diode is connected in parallel to parallel resonance circuits 15-17 respectively. Thus the diodes 11-14 have the common capacity and its change by controlling these diodes in common with each other by the voltage given from a capacity control voltage input terminal 18. Thus the resonance frequencies of circuits 15-17 are changed with approximately equal relation. As a result, the frequency band width can be changed with no deterioration of the amplitude characteristics within a pass band by changing the voltage applied to the terminal 18. |
