| 摘要 |
PROBLEM TO BE SOLVED: To enable high-accuracy compensation with the table memory of small capacity and an arithmetic logic in small scale, in the case of compensating the nonlinear distortion of a power amplifier through a predistortion method. SOLUTION: In polynomial arithmetic parts 21 and 22, amplitudes Vi and Vq of baseband signals I and Q from roll-off filters 11 and 12 are respectively substituted to a polynomial g (v) for amplitude distortion compensation, and the arithmetic results g (Vi) and g(Vq) are calculated. A square arithmetic part 23 calculates an arithmetic output Miq2 expressed as Miq2=(g(Vi))2+(g(Vq)2. Corresponding to this arithmetic output Miq2, a phase valueθin one- to-one correspondence with the arithmetic output Miq2 is read out of a table 24 for phase distortion compensation. Synthetic arithmetic parts 25 and 26 calculate baseband signals I' and Q', which are expressed as I'=g(Vi)×cosθ-g(Vq)×sinθand Q'=g(Vq)×cosθ+g(Vi)×sinθ.
|
