| 摘要 |
PROBLEM TO BE SOLVED: To improve non-linearity in the phase and amplitude of a power amplifier. SOLUTION: This device forms a modulation signal from different base band signals for controlling phase modulation and amplitude modulation. A phase control signal phi is used to control a voltage-controlled oscillator 10, and a transmission frequency signal for an RF amplifier 5 is further obtained from it. The amplitude of the RF amplitude is controlled by an amplitude control signal A. Sampling circuits 6 and 7 produce a feedback signal from the output of the RF amplifier, and the feedback signal is used separately to correct both the amplitude control and phase control, so that the transfer function of the device can be linear. Then, a used amplifier may be a nonlinear amplifier of high efficiency and even then, satisfactory linearity can be attained by using the device. |
