| 摘要 |
PURPOSE: A very high frequency input filter circuit is provided to improve a characteristic of the very high frequency input filter by reducing the number of mounted components and varying the capacity of coils. CONSTITUTION: A very high frequency input filter circuit is formed with the first filter portion(110) and the second filter portion(120) connected with a rear end of the first filter portion(110). The first filter portion(110) is formed with the first to the fourth condensers(C11-C14) and the first to the fourth coils(L11-L14). The first condenser(C11) is connected with an input terminal. The second condenser(C12) is serially with the first coil(L11). The second condenser(C12) and the first coil(L11) are connected in parallel to a rear end of the first condenser(C11). A coil(L12) is connected in parallel to a condenser(C13). The second filter portion(120) is formed with the fifth to the seventh coils(L15-L17), the fifth to the eighth condensers(C15-C18), the first and the second switching diodes(SD1,SD2), and the first and the second variable capacity diodes(VD1,VD2). |
