| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and Doherty-type amplifier capable of realizing a wide bandwidth inexpensively. SOLUTION: In a Doherty-type amplifier, a signal branched with a two splitter 4 is passed through a route composed of an A class, B class, or AB class amplifier 2 for carrier amplification and a 1/4 wavelength line 3, and supplied to a load 9. The other signal is passed through a route composed of a variable attenuator 5, a variable phase shifter 6, a 1/4 wavelength line 7, and a C class amplifier 8 for peak amplification, and supplied to a load 9. A control signal memorized beforehand is read from a control table storage apparatus 10. The 1/4 wavelength lines 3 and 7, the variable attenuator 5, and the variable phase shifter 6 are controlled by the control signal, according to a frequency information 111. Consequently, each amplitude and each phase of signals branched in two is controlled identically, even if a carrier frequency as a frequency of an input signal is changed. Moreover, since the line length of 1/4 wavelength lines 3 and 7 is also controlled according to the frequency, increase in bandwidth can be implemented without design change of a 1/4 wavelength line. COPYRIGHT: (C)2008,JPO&INPIT
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