| 摘要 |
PROBLEM TO BE SOLVED: To provide a bias circuit capable of obtaining high output with less distortion and a power amplifier using the same, and a radio communication device. SOLUTION: The bias circuit is equipped with a bias circuit 12 having a voltage dividing circuit 13 which divides a first voltage to a specified value, a capacitor C2 which has one end connected to an output terminal Vout of the voltage dividing circuit 13 and the other end grounded, a first transistor Q1 which has a base b1 connected to the output terminal Vout of the voltage dividing circuit 13 through a resistor R2 and a collector c1 connected to a second power source, and a second transistor Q2 which has a collector c2 connected to an emitter e1, the collector c2 and a base b2 connected to each other, and an emitter e2 grounded, and a power amplification section 11 having a third transistor Q3 having a base b3 connected to the emitter e1 through a coil L. A high-frequency signal Pl leaking from the coil L is bypassed through equivalent capacity Hfe1×C2 and a negative feedback resistor R2 suppresses a decrease in Hfe1 during a large-amplitude operation. COPYRIGHT: (C)2007,JPO&INPIT
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