Design and analysis of a fully integrated two-stage interleaved synchronous buck DC-DC converter with on-chip filter inductor and capacitor is presented. The DC-DC converter is designed and fabricated in a 0.18 mum SiGe RFBiCMOS process technology and generates 1.5V-2.0V programmable output voltage supporting a maximum output current of 200mA. High switching frequency, multi-phase interleaved operation, and fast hysteretic controller reduce the filter inductor and capacitor sizes by two orders of magnitude compared to the state-of-the-art converters and enable a fully integrated converter. The fully integrated buck regulator achieves 64% efficiency while providing an output current of 200 mA