Silicon has been the basis of semiconductor technology for the past couple of decades. Hence, engineersrnand manufacturers have made vast strides in silicon manufacturing, integrated circuit design, andrnsemiconductor applications. However, due to the saturation of Moore's Law in recent years, Si-basedrnsemiconductor is about to see its limit in electronics applications. Meanwhile, there's a continuing need forrnfaster, more efficient circuits. One of the paths forward from this point is for researchers and companiesrnalike to look towards different materials to produce the devices of tomorrow. One material in particular thatrnhas caught the attention of the industry is gallium nitride (GaN). GaN power devices have lower specificrnon-resistance and faster switching speeds when compared to silicon power devices. These attributes makernthe GaN devices attractive for applications in the high efficiency class D audio amplifiers, a field that hasrnnot been widely studied. To that end, this thesis work set out to compare the performance of GaN basedrnclass D amplifiers with their Si counterparts. A class D audio amplifier was designed in the full bridgern(bridge tied load â€“ BTL) topology having a second order Butterworth filter for its output. The GaN basedrnclass D circuit had a high efficiency of about 97.7% while the Si had 85.7% at 100kHz switching frequency.rnIt was also observed that as the switching frequency increased the efficiencies decreased. The GaNrnefficiency decreased to about 89.5% and the Si to 63.1% at 800kHz. This concludes that GaN class Drnamplifiers are certainly better than Si, especially for higher switching frequencies.