| 摘要 |
PROBLEM TO BE SOLVED: To control a gain only at a positive potential by parallelly connecting a high resistance element for impressing the positive potential to a FET for gain control for which one end of current passage is connected to a circuit to control the gain. SOLUTION: This circuit is provided with a depression type MESFET 21 connecting the drain to a high frequency power amplifier circuit 100 having an input terminal 1 and an output terminal 7, connecting the source to a power feeding terminal 25 and connecting the source to a gain control terminal 16. A high resistance element 22 of 10kΩ, for example, is parallelly connected between the source and drain of the MESFET 21. Thus, the positive potential can be impressed between the drain and source of MESFET 21 and the gain control of high frequency power amplifier circuit 100 can be performed only by the signal of positive potential.
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