FIELD: controlling nonlinear distortion characteristics in radio communication system transmitter. SUBSTANCE: device has predistortion unit 1 for pre- shaping nonlinear distortion characteristic opposing those occurring in output amplifier 22; step-up converter 20 that functions to convert output frequency of predistortion unit into radio-frequency band and to send converted frequency to output amplifier 22; check-up unit 44 for checking output level across output amplifier 22; memory unit 42 for pre- memorizing nonlinear distortion characteristics of predistortion unit 1 in the form of digital data; distortion controller 46 for output and control of digital data on definite nonlinear distortion characteristic stored in memory unit 42 according to output level across check-up unit 44; digital-to-analog converter 40 for converting digital data on nonlinear distortion characteristic arriving from distortion controller 46 into analog signal and applying converted data to predistortion unit 1. EFFECT: enhanced accuracy of correlating distortion characteristics of predistortion unit and output amplifier. 5 cl, 4 dwg
