| 摘要 |
PROBLEM TO BE SOLVED: To handle load fluctuation and an overload state by one RF power amplifier to be used in common for saturation type nonlinear amplification and non-saturation type linear amplification. SOLUTION: The RF power amplifier 100 includes a final-stage amplification stage 11 which generates an RF transmission output signal P<SB>OUT</SB>, a signal detector 13 which detects an RF transmission output level, a first detector 14, a second detector 17, and control circuits 15, 16, and 18. The final-stage amplification stage 11 includes a transistor Qn2 and a load element L2, and performs the saturation type nonlinear amplification and non-saturation type linear amplification. The first detector 14 is supplied with an RF detection signal from the signal detector 13 and the second detector 17 is supplied with the output voltage Vds from the final-stage transistor Qn2. The first detector 14 and control circuits keep the RF transmission output signal P<SB>OUT</SB>nearly constant through the saturation type nonlinear amplification against antenna load variation. The second detector 17 and control circuits reduce an increase in the output voltage Vds of the final-stage transistor through the non-saturation type linear amplification in an antenna overload state. COPYRIGHT: (C)2010,JPO&INPIT
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