Systems and method related to switchable output stages in power amplifiers. A rank aggregation system provides an order-based aggregation of rankings of entities by learning weights within an optimization framework for combining the rankings of the entities using labeled training data and the ordering of the individual rankings. The modular components may be added to and removed from the system easily to allow for flexibility in the operation of the system. The passivation layer is patterned to define a plurality of first and second access openings respectively about a plurality of first solder wettable pads and at least one second solder wettable pad on the metal layer.