Linearization of power amplifiers has been the topic of many studies, dating back to the work of H. S. Black in the 1920s. For many applications, the well-documented techniques of feedforward and feedback can be used to design low intermodulation distortion (IMD) amplifiers. However, certain applications, including the design of high-power, radio frequency amplifiers, preclude the use of these techniques. The work herein describes an alternative to presently accepted distortion reduction techniques. In-band IM distortion (multi-tone distortion located close in frequency to the desired signal) , is reduced by modifying a baseband input, upconverting this signal to the transmission frequency, then performing the amplification. This allows DSP hardware to be used, resulting in a novel IMD reduction method. The approach presented is unique in that multiple orders of nonlinearity are reduced using DSP technology, at baseband, through a commonly used method of upconversion. Existing work has addressed mostly third-order, analog solutions applied at the frequency of transmission. Theoretical work, simulations, and experimental results are used to describe the technique. Advantages and limitations are discussed, as are areas for future work.
Library of Congress Subject Headings
Signal processing--Digital techniques--Data processing; Amplifiers (Electronics)
Department, Program, or Center
Electrical Engineering (KGCOE)
Buckley, Richard James, "A Digital signal processing-based predistortion technique for reduction of intermodulation distortion" (1993). Thesis. Rochester Institute of Technology. Accessed from
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