| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption by changing load impedance of a power amplifier so that the efficiency of the power amplifier is optimum in a communication system that performs frequency division multiplex. SOLUTION: A variable impedance circuit 20 is provided between a power amplifier 10 and a band pass filter 30 and is controlled by a controlling part 40. At the time of performing frequency division multiplex, when a frequency band to be used changes, load impedance of the amplifier 10 also changes. However, load impedance that always optimizes the efficiency of the amplifier 10 is acquired by controlling the circuit 20 with the part 40. |
