DSP oriented implementation of a feedforward power amplifier linearizer

Abstract

In this contribution we introduce a new digital signal processing (DSP)-oriented implementation of a feedforward linearizer. The intermodulation distortion (IMD) signal is regenerated entirely in the digital baseband which gives better control over the linearization process and also improves the efficiency of the overall amplifier. A new scheme to estimate the parameters of the proposed feedforward linearizer is presented which decouples the parameters of the signal and error cancellation loop. We have verified the new DSP oriented feedforward linearizer by means of simulations in the presence of component impairments like, e.g., IQ mismatch. Initial measurements results in a laboratory setup show a reduction of the adjacent channel power of approximately 15 to 20 dB.

Performance of feed‐forward linearizers of power amplifiers in OFDM systems under complex gain errors

“…It was shown that the directivity of the directional couplers has a significant effect on the amplitude imbalance of the FF circuit. In [35], the authors proposed a DSP-oriented FF scheme that decouples the parameters of the signal and error cancelation loops. The proposed scheme was analyzed in the presence of in-phase-quadrature (IQ) mismatch in the IQ demodulator, which is used to convert the signal to baseband for estimation of complex gains in DSP.…”

Smart RF signal processing for advanced transmitters: From theory to practice

“…predistortion [4,8], and digitally assisted hybrid compensation, e.g. feed-forward [9] or mixer IP2 calibration [10]). With such techniques, the impairment compensation can easily follow the changes in operation frequency and bandwidth.…”