As systems designers work hard to squeeze more and more features into less board space, the power delivery paths are becoming increasingly complex. The current mature VRM designs based on Silicon MOSFETs are hardly meeting present day requirements. One of the promising technologies touted to solve this conundrum of space and performance constraints is GaN HEMT. However, many engineers are hesitant to design very high frequency GaN VRMs from the ground up. This paper evaluates the steps required to modify existing Si-MOSFET designs for use with eGaN HEMT devices. The paper also compares the expected performance of GaN vs. Si in linear and switching regulator topologies and covers some of the measurement challenges as well.