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UBC Theses and Dissertations

A new radio frequency switch-mode power amplifier concept for wireless applications Ali, Sheikh Nijam


Although RF switch-mode power amplifiers (SMPAs) are theoretically attractive with the potential to achieve very high power efficiencies, experimental realizations at high frequencies have yet to yield significantly better efficiency than conventional analog technology. Most SMPA designs are based on class D or class S circuits, and in these circuits, power efficiency is significantly reduced when the switching signal is changed from periodic to non-periodic. In this work, a new SMPA architecture is proposed. Instead of employing reflective out-of-band matching conditions used in class D/S circuits, the switch is matched to a broadband load which creates dissipative out-of-band impedances. The broadband load significantly improves switching conditions especially for non-periodic signals. The broadband load is implemented as a complementary diplexer which separates in-band and out-of-band signal power at the output of the SMPA. An energy recovery loop using out-of-band signal power is proposed to significantly reduce the sensitivity of the overall power efficiency to changes in the peak to average power ratio of the source signal. Experimental and simulation results are shown for the new SMPA architecture.

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