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Patent Searching and Data


Title:
INPUT FILTER CIRCUIT FOR CATV CONVERTER TUNER
Document Type and Number:
Japanese Patent JPS63313986
Kind Code:
A
Abstract:
PURPOSE:To control a disturbance component that leaks into an input irrespectively of reception channel and to improve backtalk by using two or more variable traps whose trap frequency variation rations are different from each other between a signal route between an input terminal and a first mixer and the ground. CONSTITUTION:The variable trap consisting of a series capacitor 4, a coil 5, and a varactor diode 6 is provided between the signal line between the input terminal 8 and a first mixer 10 and the ground. A tuning voltage is supplied through a tuning voltage supply resistor 7 to vary the capacitance of the diode 6 and the trap frequency. Two or more traps whose changing ratio of the frequency number of trap to said variable trap is different are provided. As a result, at the time of receiving in a low-band channel, wide range from intermediate band to high band is attenuated, and at the time of intermediate channel reception, the trap frequency comes out of the receiving band.

Inventors:
NAKAMURA HIDEAKI
ASAI SEIYA
Application Number:
JP14897687A
Publication Date:
December 22, 1988
Filing Date:
June 17, 1987
Export Citation:
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Assignee:
HITACHI LTD
International Classes:
H03H7/075; H04N5/44; H04N7/16; (IPC1-7): H04N5/44; H04N7/16
Attorney, Agent or Firm:
Katsuo Ogawa