Optimized biasing condition for high efficiency power amplifier based on cascode cell

Closed-form relationships for the optimum bias point of high efficiency and widband power amplifiers (PAs) based on cascode cel are presented in this contribution. Through a rigorous analysis, the optimum output load, supply voltages, expected output power and efficiency of a cascode PA are derived and compared with those of the standard common source PA. Benefits of the proposed solution with respect to the classical biasing approach of a cascode PA are shown as well. Based on the same active device, a common source PA and a cascode PA are designed, realized, characterized and compered to validate the performed analysis. The results demonstrate that the proposed solution allows to obtain a cascode PA with output power and efficiency levels similar to those of the common source PA and a frequency band three times wider.