Among the depth range finding methods, the ToF (Time-of-flight) method is widely used in many applications. In this paper, some limitation of ToF method is discussed. Therefore, we proposed the phase offset technique to extend the detectable range. On base of that, we analyzed and evaluated this design of the shifter. Then we compared this method with conventional range extension methods. Finally, we point out the feasibility of the proposed technique and discuss its advantages and drawbacks.