Navigating Challenges in Doherty Power Amplifier Design for Millimeter-Wave Frequencies

The paper addresses some of the challenges associated with implementing multi-stage Doherty power amplifiers at millimeter waves. The routing of the bias lines is analyzed for several configurations, including two-way and three-way, highlighting how it can impact performance in the presence of significant crosstalk between the metal layers in integrated technologies. Additionally, the paper discusses and provides a quantitative estimate of the Doherty gain penalty with respect to corporate amplifier configurations, a factor that may hinder the adoption of this architecture at millimeter waves and that calls for a careful trade-off between intrinsic technology gain and number of driver stages.