The present application relates to a method for operating sensing signals and the circuit thereof. An analog-to-digital converter first processes the input signal having the most significant bit (MSB DATA) data at least once. Afterwards, the analog-to-digital converter processes the input signal having the least significant bit (LSB) data and the MSB data and sums all the input signals. Thereby, the process steps of the analog-to-digital converter can be simplified and the processing time can be shortened.