In this paper, the architecture of a 2-bit photonic digital-to-analog converter (DAC) based on an integrated optoelectronic circuit consisting of two microring resonators and two 1×2 optical splitters, which can transform a 2-bit electrical digital signal to optical analog signal. As a proof of concept, a 2-bit photonic DAC is fabricated in the silicon-on-insulator (SOI) platform by CMOS-compatible process. Two microring resonators are both modulated through thermo-optic effect by micro-heaters embedded above the ring waveguides. The analog optical output is detected at the output port of the circuit. A 2-bit photonic DAC operating at 50Ksamples/s is demonstrated.