| 摘要 |
PURPOSE:To provide the power amplifier which is highly efficient and has a satisfactory linearity by controlling a level compressor and an efficient power amplifier in accordance with an input signal level. CONSTITUTION:A level detector 1, a level compressor 2, a power amplifier 3, and a voltage control circuit 4 are provided. The input signal is inputted to a conventional power amplifier 3 after being preliminarily compressed. That is, the signal corresponding to the input signal level detected by the level detector 1 is not only inputted to the conventional power control circuit 4 for improvement of efficiency but also used as the control signal of the level compressor 2. In this case, the inclination of input/output characteristics of the level compressor 1 is so set that input/output characteristics of a conventional power amplifier a voltage control circuit are compensated, and thereby, the inclination of synthetic input/output characteristics is 1:1 and a satisfactory linearity is realized. The level compressor 2 used in this case utilizes the saturation characteristic of the amplifier. |
