# Optimum Number of Transistors in Stacked CMOS Millimeter-Wave Power Amplifiers

This paper proposes how to define the optimum number of stacked transistors in a multi-stacked CMOS power amplifier (PA) topology, based on several physical as well as circuit design aspects. Starting with a systematic concept, the analysis then goes through the relevance of transistor transconductance, aspect ratio, parasitics, operating frequency, and the number of transistor stages in a pentagonal trade-off concept. While this is done based on theoretical circuit analysis, the results, then, are evaluated using simulations based on 45nm CMOS technology.