I. Introduction
Baluns are used to transform an unbalanced input signal into a balanced output signal. Baluns are essential components in many microwave circuits, e.g., balanced mixers and differential amplifiers. Baluns can be split into active and passive types. Active baluns use transistors to overcome losses found in passive baluns and allow for compact circuits in MMIC processes. The main drawback of active baluns is that they limit the dynamic range of the balanced mixer or amplifier significantly.