| 摘要 |
PURPOSE: To obtain the variable band adjustment circuit in which band adjustment is simply and continuously conducted so as to adjust a band without deteriorating a transmitted main signal. CONSTITUTION: A parallel connection circuit comprising a band adjustment resistor 3 and a varactor diode 4 is connected between an AC coupling capacitor 1 connecting to an input terminal 10 and an AC coupling capacitor 2 connected to an output terminal 20. Then the resistor 3 and the varactor diode 4 forms a high pass filter having a low frequency cut-off frequency 1/(2πRC) depending on the resistance value R(ohms) of the resistor 3 and the capacitance C(F) of the varactor diode 4. The low cut-off frequency of the high pass filter is changed by a change in the capacitance C of the varactor diode 4 due to a change in the band adjustment voltage applied via a resistor 6 to a cathode of the varactor diode 4.
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