Performance Investigation of AMPR algorithm for Out-phased Power Amplifiers

Designing Power Amplifiers has been the center of many researches around the world, and the main idea is always to reduce the power waste and improve the efficiency. Among many proposed designs, Out-phased PA provides outstanding power efficiency, however it suffers from a phenomena known as zero crossing. The zero crossing causes unwanted elements in frequency domain which leads to bandwidth leakage and so reducing the efficiency. Therefore analyzing the zero crossing and optimizing this phenomena is crucial. Recently a parameter is defined to measure the probability of this problem. This parameter is named Average to Minimum Power Ratio (AMPR). The probability of a modulated signal experiencing high AMPR is analyzed with Complementary Cumulative Distribution Function (CCDF). An approach is investigated to target the zero crossing effect and attempt to reduce the AMPR, and so the bandwidth expansion outcome. It is expected that by using the algorithm of AMPR reduction to Digital Signal Processing (DSP) segment before the SCS, the Error Vector magnitude or Mapping (EVM) is maintained.