| 摘要 |
PURPOSE:To form a modulator and a mixer circuit with a stable action by inserting a diode between the second gate and the earth of the dual gate FET. CONSTITUTION:A signal and station transmitting signal are inputted from input terminals 1-3, and an intermediate frequency signal is removed from an output terminal 4. Here, a diode 11 inserted between input terminals 2 and 3 and an earth makes the excessive station transmitting signal input and the excessive direct current bias flow to the earth. The diode makes the excessive input flow to the earth both in the forward direction and in the reverse direction, and must leak at the pressure resistance lower than the gate pressure resistance of FET, and therefore, the diode 11 needs to obtain the shape such as a pair of two facing diodes. The diode, which satisfies these conditions, functions as a protective circuit of the mixer or the modulator. Thus, while skewness characteristics are kept satisfactorily, destruction due to an excessive input can be prevented, and the mixer and the modulator with the stable action can be realized.
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