| 摘要 |
PURPOSE:To enable the input tuner circuit of a tuner used for a TV receiver, etc., to operate in both VHF and UHF bands, by using a two-point tuner circuit which can tune to two kinds of signals of different frequencies at the same time. CONSTITUTION:To the circuit obtained by connecting the 1st and 2nd coils 5 and 6 together in series, the 1st capacitor 3 is connected in parallel, and the 2nd capacitor 4 is connected in parallel to coil 6 to constitute two-point tuner circuit 7 which resonates with two different frequencies at the same time, so that signals of two frequency bands or more can be received by varying capacity of capacitor 4. To equivalent resistance 40 of the high-frequency input signal supply, capacitor 25 is connected which applies a signal of the UHF band to the 1st capacitor 24 of circuit 7 and the connection point of coil 20, and switching diode 19 for band switching is provided which receives a VHF signal from the dividing point between the 2nd coils 21 and 22. In addition, capacitor 38 is also provided which couples the connection point between coil 20 and capacitor 24 with output equivalent resistance 41. |
