Wide Bandgap (WBG) semiconductor materials are shaping day-to-daytechnology by introducing powerful and more energy responsible devices. These materials have opened the door for building basic semiconductor devices which are superior in terms of handling high voltages, power and temperature which is not possible using conventional silicon technology. As the research continues in the field of WBG based devices, there is a potential chance that the semiconductor industry can save billions of dollars deploying energy-efficient circuits in high power conversion electronics. Diamond, silicon carbide and gallium nitride are the top three contenders among which diamond can significantly outmatch others in a variety of properties. This thesis describes a methodology to develop the ‘Simulation Program with Integrated Circuit Emphasis’ (SPICE) model for diamond-based P-I-N diodes. The developed model can predict the AC and DC response of fabricated P-I-N diodes. P-I-N diodes are semiconductor devices commonly used to control RF and microwave signals. It has found a very unique place in the list of available semiconductor devices in modern electronics which interestingly shows resistance modulation property in high frequency domain while handling a high-power signal at the same time. The developed SPICE model for the diamond-based P-I-N diode in this project is then used to evaluate the performance of a solid-state passive limiter in shunt configuration which protects the sensitive instruments in ‘Radio Detection and Ranging’ (RADAR) systems