| 摘要 |
PURPOSE:To obtain a sufficient attenuating quantity variable range even in case of a mobile radio set by inserting a variable capacity diode serially to a high frequency signal channel, inserting the impedance element in parallel, impressing the control voltage for the capacity variable to the former and changing the partial pressure ratio of the high frequency signal to the above- mentioned both elements. CONSTITUTION:Into a high frequency signal channel, variable quantity diodes VD1-VD3 are serially inserted, and PIN diodes D1 and D2 are inserted in parallel. To the diodes VD1-VD3, the control voltage of the reverse bias is impressed by the direct current control voltage source of a terminal 14. At the diodes D1 and D2, the control bias electric current flows in the forward direction through coils 21 and 22 for stopping the high frequency. For this reason, when the control voltage is high, the large bias electric current flows at the diodes D1 and D2, the resistance value goes to be low, the high reverse bias voltage is impressed to the diodes VD1-VD3 and the impedance goes to be high. Consequently, the rate of the high frequency signal impressed to the diodes VD1-VD3 goes to be large and the high frequency signal receives the large attenuation.
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