| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit which can be operated stably by preventing oscillation in a high frequency band and has low noise and a high gain. SOLUTION: The drain and the gate of an FET 1 are connected via a voltage negative feedback portion 11, and a resistance component connected between the drain and the gate of the FET 1 is divided into two resistors, with one resistor R1 arranged near the drain and the other resistor R2 arranged near the gate. Between ground and a connecting point between a capacitor 4 and the gate-side resistor R2 which are included in the voltage negative feedback portion 11, a capacitor C3 having a small capacitance is connected. The capacitance of the capacitor C3 is set to such a value that the capacitor C3 may become a high impedance at a low frequency corresponding to the broadcast band while making the voltage negative feedback portion 11 become a low impedance at a high frequency. A ground pattern 23 immediately below the drain and gate of the FET 1 is cut out to form cutout portions 24 and 25. COPYRIGHT: (C)2009,JPO&INPIT
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