A thorough circuit simulation model for the GaN technology, which is in high demand globally and even in India, particularly in the quest of realizing the Indian net-zero objective by 2070, through the design of energy efficient circuits. As of now, my model, which is known as the Advanced SPICE model for GaN HEMTs (ASM-GaN-HEMT) is widely popular globally and even has relevance in the Indian scenario. Presently, several companies, that are actively manufacturing GaN based products, such as Infineon, Texas Instruments, Toshiba, Cree, Qorvo, Boeing and many other GaN based startups, are using the ASM model for their designs. Even the Indian research agencies such as ISRO and DRDO are active users of the ASM model. This model was a culmination of my PhD work carried out at IIT Kanpur, and I continue to do research on the said topic here at NIT Srinagar with my research group, where significant developments in the work were made through our SERB funded project under the Startup Research Grant scheme (earlier known as the Early Career Research Award), with several IEEE Transactions published through its sponsorship.