| 摘要 |
PROBLEM TO BE SOLVED: To make damage less likely for a broadband amplifier which is apt to be broken down by static electricity, etc., without increasing the number of parts to be used. SOLUTION: This circuit comprises an input end 1 connected to an antenna; a low-noise broadband amplifier 4 for amplifying all television signals input to the input end 1; an electrostatic discharge device 3 provided between the input end 1 and the low-noise broadband amplifier 4; and a highpass filter 2 which passes the lowest frequency or higher of the television signal. The highpass filter 2 is constituted by aπ-type filter having at least a capacitance device 2b, interposed in series between the input end 1 and the low-noise broadband amplifier 4; a first inductance device 2a which shunts one end of the input end 1 of the capacitance device 2b to a ground; and a second inductance device 2c, which shunts the other end of the capacitance device 2b to the ground. A signal line between the input end 1 and the capacitance device 2b is connected to the ground by the electrostatic discharge device 3.
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