| 摘要 |
PURPOSE:To improve the capability excluding an image disturbance signal and a local oscillation disturbance signal by adding a filter having a pole attenuating each of the image disturbing signal and a local oscillation disturbing signal to a desired signal to a receiver input circuit. CONSTITUTION:Filters 1, 2 are added to the input circuit. The local oscillation disturbing signal of an inputted radio wave is blocked by a coil 7 and a capacitor 8 constituting the 1st filter of the filter 1 via a matching coil 4. Further, the image disturbing signal is blocked by a coil 9 and a capacitor 10 constituting the 2nd filter via a matching coil 5. On the other hand, the desired signal passes through matching coils 4, 5, 6 and the band pass filter 2 and reaches a filter output 16. In this case, the coils 7, 9 are adjusted and set so as to minimize a disturbing beat sound caused when the desired signal, the local oscillation disturbing signal and the image disturbance signal are received at the same time. |
