This work demonstrates the design of the digital half adder at the data rate of 1Mbit/s using micro-ring resonators (MRRs). In order to obtain the response of Sum and Carry ports, three micro-ring resonators are used, and a thermo-optic effect is achieved by placing micro heaters on top of each ring. All rings used in the design have identical parameters. Static and dynamic responses of the circuit are provided to show the ability of the device to work properly, and the obtained power level demonstrates that the circuit can transmit data at a specified speed without any additional active elements. The design achieved a compact size of about 658 × 486 µm2.