| 摘要 |
PROBLEM TO BE SOLVED: To prevent radio disturbances such as interference and oscillation. SOLUTION: Received signals to be input into a first transformer T1 for mixing are supplied via capacitors C1/C5 having a small capacity of about 5 pF. A midpoint of the first transformer T1 is connected to a midpoint of a second transformer T2 via a bandpass filter. The bandpass filter comprises a series circuit of a capacitor C3 resonant with about 1,600 MHz, a capacitor C2 resonant with about 222 MHz and a coil L5. A mixed output from the second transistor T2 is output via a capacitor C4 having a small capacity of about 5 pF. Received signals of 470-770 MHz digital terrestrial broadcasts can thus be mixed without radio disturbances such as interference and oscillation. COPYRIGHT: (C)2012,JPO&INPIT |
