| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem such that an idle current Idsq is considerably dispersed since a threshold voltage Vth is considerably dispersed by a production lot or the like concerning an FET for high frequency such as GaAsFET in the bias circuit of a resistance dividing system. SOLUTION: The reference voltage of a reference voltage source 132 is impressed to the gate of one FET 112 comprising a differential amplifier, a voltage drop in a resistor 143 for monitoring the current of an FET 115 as a replica of an FET 111 for RF amplification is impressed to the gate of another FET 113, the both are compared, the drain voltage of the FET 112 is fed back to the respective gates of the FET 111 and 115, and common mode feedback is applied from the drain of the FET 113 to a current source FET 114.
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