Piecewise Pre-Equalized Linearization of the Wireless Transmitter With a Doherty Amplifier

• Published in: IEEE transactions on microwave theory and techniques Vol. 54; no. 9; pp. 3469 - 3478
• Main Authors: Wan-Jong Kim, Kyoung-Joon Cho, Stapleton, S.P., Jong-Heon Kim
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adjacent channel power ratio (ACPR); Amplifiers; Amplitude modulation; Applied sciences; Broadband amplifiers; Circuit properties; digital predistorter (PD); Doherty power amplifier (DPA); Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Finite impulse response filter; finite-impulse-response (FIR) filter; Frequency filters; Hammerstein; Linearity; Linearization techniques; lookup table (LUT); memory effects; memory polynomial; Multiaccess communication; Polynomials; Predistortion; Radio frequency; Radiocommunications; Telecommunications; Telecommunications and information theory; Transmitters; Transmitters. Receivers; Performance evaluation; Adjacent channel power ratio (ACPR); Doherty power amplifier (DPA); Wireless telecommunication; Transmitter; Equalizer; Polynomial method; Non linear phenomenon; Digital filter; digital predistorter (PD); memory polynomial; Wide band; Hammerstein equation; Peak power; finite- impulse-response (FIR) filter; Multitone system; Adjacent channel; Look up table; Hammerstein; memory effects; Simulation; lookup table (LUT); Finite impulse response filter; Power amplifier; Non linear effect; Multiple channel; Memory effect; Signal distortion; Piecewise linearization
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2006.880639

This paper describes a predistorter (PD) based on piecewise pre-equalizers for use in multichannel wideband applications. The predistortion linearizer consists of piecewise pre-equalizers along with a look-up-table-based digital PD that together compensate for nonlinearities, as well as memory effects of power amplifiers (PAs). It takes advantage of multiple finite-impulse-response filters that significantly reduce the complexity when compared to memory polynomial methods. The proposed method was also compared with the conventional Hammerstein structure. A 300-W peak envelope power Doherty PA was first modeled by measured time-based samples in order to verify the adjacent channel power ratio (ACPR) performance in simulation using a multitone and single wideband code-division multiple-access (W-CDMA) carrier. Furthermore, the experimental results applying two W-CDMA carriers verify that the proposed method provided similar improvement to that of the memory polynomial approach. The experimental results verified the complexity reduction and superior ACPR performance over the conventional Hammerstein structure