| 摘要 |
PURPOSE:To improve the distortion characteristic at maximum gain time in a high frequency amplifier using a dual gate FET, selecting one gate to apply an AGC voltage by connecting one gate with a source through a resistor. CONSTITUTION:A dual gate FET monolithically integrated in a semiconductor integrated circuit and a bias resistor 21 in an enclosure designated by a broken line are formed. The resistor is connected between the second gate G2 of the FET applied with the AGC voltage through a bias resistor 22 and a source S, the resistor 21 is selected to 1kOMEGA or larger, several 1OMEGA or less, and an input side bias resistor 22 is set to a value sufficiently larger than the value of the resistor 21. Then, a voltage VG23 between the second date G2 and the source S is fixed to approx. 0V. The second gate G2 is bypassed by a capacitor 23. Thus, the second gate voltage is set to substantial 0V to improve the distortion characteristic at the maximum gain time.
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