Design of 5th-order analog predistorter

This paper presents the design of a 5^th-order analog predistorter to suppress the 3^rd-and 5^th-order intermodulation distortion products (EVTDP3 and EVTDP5) at the output of a base-station power amplifiers (PAs). The predistorter consists of two mixers: one mixer generating the 3^rd-order intermodulation (IM3) products and another mixer of same configuration generating the 5^th-order intermodulation (IM5) products using the IM3 products generated by the other mixer, thus simplifying the design and hardware implementation. The predistorter is implemented and tested using two-tone and the CDMA (IS-95) signals at 2.2 GHz in a practical 10 W-PA. The two-tone test results show that the proposed predistorter can suppress the IMDP3 and IMDP5 by 17 dB and lldB, respectively. For the CDMA (IS-95) test, results show that the predistorter can improve the adjacent channel power ratio (ACPR) by 10 dB at + 887 kHz from the center frequency.