| 摘要 |
PURPOSE:To remove effectively a specific frequency component on a line without varying the DC characteristics of the line, requiring a large-capacity element, and causing large loss by connecting negative-phase amplifier input and output signals to the line to be given filter characteristics through an AC coupling means. CONSTITUTION:The inverted input terminal of an operational amplifier A is connected to a line ls through a resistance R1 and a capacitor C1, the uninverted input terminal is connected to an earth line le, and the output is connected to the inverted input terminal through a resistance R2 and also connected to the line ls through the capacitor C2. The operational amplifier A is powered on by a power source E to operates as a negative-phase amplifier having a gain determined by the resistances R1 and R2. A voltage obtained by as many times as the gain appears at the output terminal of the line ls. Consequently, desired filter characteristics are obtained without any variation in the DC characteristics of the line nor using a large-capacity capacitor nor inductance, and the circuit is reduced in size.
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