Electronically switchable microwave filters are attracting more attention for research and development because of their importance in increasing the capability of wireless communication and cognitive radios. In this paper, novel switchable microwave band- stop to all pass fliters are designed by using stepped impedance resonator. Commercially available Pin diodes are used in order to allow the fastest switching between band-stop and all pass responses. The theoretical analysis is presented in this paper, and its feasibility has been experimentally verified with a micro-strip prototype. The design was also characterized by measuring the filter performance with increasing power levels of 20, 15, 10, 5, and 0 dBm. The results have shown that the switchable filter is immune to power saturation e®ects .Nonlinear measurements at higher power levels are also performed and the switchable filter produced low power inter-modulation product. The main advantage of this filter is its capability to switch between band-stop and all pass mode of operation. Other advantages include being small in size, and low in cost.