| 摘要 |
PURPOSE:To attain a low cost and miniaturized tuner by extracting a local oscillating signal for PLL frequency synthesizer by an extracting circuit with a simple form made by the combination of a resistor and a capacitor in the extracting circuit of an oscillating signal of an electronic tuner for the television receiver or the like. CONSTITUTION:The oscillating signal of the 1st and 2nd local oscillators 20, 21 is extracted from an input terminal via a resistor 23 and outputted from a terminal 27. Further, the oscillating signal of the 3rd local oscillator 22 at UHF receiving is extracted via a resistor 25 and a capacitor 26 by the coupling of a coil 24 and an oscillator, and outputted from the terminal 27. The coil 24 is constituted by using leads of the resistor 25. The capacitor 26 has a comparatively small capacitance to prevent the loss of an RF signal of the VHF band via the resistor 23. Thus, the oscillating signal level of -35--25dBm is obtained over entire band from the UHF to the VHF. Moreover, the resistor 23 is 330ohms, the resistor 25 is 100ohms, the capacitor 36 is 5pF and the measurement is executed under 50-ohm termination. |
