Monolithic microwave integrated circuits (MMICs) have become an important and integral part of our lives today. Modern day MMICs can be found in a wide range of applications ranging from commercial products such as the cellular communication systems to complex satellite systems and radar systems used in the defence industries. The advancement in the field of MMICs in terms of its performance and compactness in size is the result of the union between the understanding in microwave/millimeter-wave frequencies theories and microelectronics fabrication competencies. The active device which is the key component for MMICs has seen tremendous progress over the past fifty years not solely in terms of the frequency of operation but also the achievable output power density [1]. For example, indium phosphide (InP) based double heterojunction bipolar transistors had demonstrated a f max of greater than 800 GHz [2], silicon germanium (SiGe) and CMOS based RFICs working above 100 GHz [3], and AlGaN/GaN based power amplifiers operating in the W-band frequency spectrum [4],[5]. A GaN power amplifier design capable of achieving pulsed output power of greater than 400W with PAE greater than 40% across the frequency range from 2.9 GHz to 3.5 GHz was demonstrated [6]. GaN power amplifier capable of achieving pulse output power of 750W was also demonstrated but has a narrow bandwidth performance at 2.14GHz [7].As listed above, each material will have traits superior to others and selecting the appropriate material system to be used in circuit design will depend on the intended application. Certain materials such as InP and GaAs are more proficient in high frequency operation (beyond w-band operation) while material such as GaN display superiority when used in high power applications.