Delta-Sigma Modulation Applied to Switching RF Power Amplifiers

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Background:The task of this thesis is to investigate the possibility of using non-linear high efficiency switching power amplifiers with spectrally efficient varying envelope modulation schemes and, if possible, further investigate such a solution on a high level.The thesis focuses on the theory necessary to understand the technical issues related to power amplifiers and the procedures behind simulating and measuring the characteristics of different power amplifier configurations. The thesis also covers basic theory behind Delta-Sigma-modulators. The theory is needed to draw conclusions about the feasibility of using a Delta-Sigma-modulator as input to a switching amplifier.Results:Using a Delta-Sigma-modulated input to a switching amplifier inherently degrades the performance, mainly because of poor coding efficiency and high switching activity. However, by merely using a switching amplifier as a mixer it is shown to be possible to transmit a non-constant envelope signal, with digital logic. The resulting circuit is, however, not an amplifier and it should not be seen as the final result. As already mentioned: the result lies in the investigation of a using Delta-Sigma-modulator as input to a switching amplifier.Conclusion:From this investigation we believe that the widely known technique: pulse width modulation (PWM), together with a tuned switching amplifier and some linearization technique, for example pre-distort...