This thesis recounts an internship at Infineon Technologies within the Power Supply and Sensors (PSS) department, with a primary focus on Analog Power IC Design, particularly in the context of AC-DC flyback topology. The internship commenced with an intensive training program encompassing fundamental analog block design principles, including topics such as bandgap reference and operational amplifiers (OpAmps). Basic analog circuit block, such as the bandgap current reference and a two-stage operational transconductance amplifier (OTA), were developed during this training period, with simulation results detailed in Annex. The core of this thesis comprises two primary sections, each delving into crucial components within the primary IC of the AC-DC Flyback Converter: the Current Sensing Block and the Gate Driver Block.