| 摘要 |
A linear compensating circuit is provided which comprises a first level detection circuit for detecting the level of an input signal to an amplifier, a second level detection circuit for detecting the level of an output signal from the amplifier, an amplitude compensating circuit for controlling the amplitude of the input signal in accordance with the difference between the signal level detected by the first detection circuit and the signal level detected by the second level detection circuit for improving the linearity of an input-output characteristic of the amplifier, and a phase compensating circuit for controlling the phase of the input signal in accordance with the signal level detected by the second detection circuit. This linear compensating circuit performs the compensations of amplitude and phase and as a result, the degradation of phase characteristic induced due to the compensation of amplitude can be prevented, resulting in a reduction in the distortion of an output signal of the amplifier even when it is being operated in the vicinity of the saturation range. This linear compensating circuit is effective when applied to a power amplifier, particularly to a high frequency power amplifier. It has a characteristic set preferably to cancel the phase change of the output signal induced caused by the compensation of amplitude by the amplitude compensating circuit. <IMAGE> |
