| 摘要 |
PURPOSE:To prevent the reduction in power efficiency even to the FM mode or the like by providing a mode switching control means outputting a matching switch signal and a bias current suitable to the mode set with the communication mode including at least the FM mode, the AM mode and the SSB mode so as to suppress the increase in the device scale and the cost. CONSTITUTION:The mode switching control means 10 outputs matching switch signals VX1, VX2 and a bias current IB in matching with the FM mode, AM mode and SSB mode, at least one communication mode, set by the mode setting signal VM. Thus, the bias of the transistor power amplifier circuit 2 is decided by the bias current IB suited to the set mode, the amplification mode such as class A or B is decided and the impedance matching with the external circuit is attained by the input matching circuit 1 and the output matching circuit 3 in response to the amplification form. Thus, the increase in the device scale and high cost are suppressed and the maximum power efficiency is obtained for each communication mode.
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