| 摘要 |
PROBLEM TO BE SOLVED: To adjust an unbalance of an IM level when compensating nonlinear characteristics. SOLUTION: Input/output demodulation sections A and B extract a baseband signal in the RF input/output of an RF amplifier, a delay detection section E detects a time difference and a phase difference between both signals, a delay adjustment section C adjusts synchronization, and the output demodulation section B adjusts phase. In this state, a distortion detection section F obtains distortion components by the amplitude and phase errors in both the signals, a distortion correction section D obtains the amount of compensation corresponding to the distortion components, the amount of compensation is added to a signal obtained by the input demodulation section A to compensate the distortion components, and an output conversion section G makes conversion to an original signal format for outputting to an RF amplifier. In this case, each IM level at the lower and upper ends of the transmission band in the RF output signal in a compensation state is detected by an IF detection section H, and an angle correction section 54 in the distortion detection section F corrects the inclination of amplitude-phase characteristics Δθ in the distortion component, so that each IM level becomes equal at the lower and upper ends and adjusts the amount of compensation based on the detection result. |
