An active snubber cell and its dual circuit for reducing switching losses of 1 to N phase dc-dc converters is presented. Main switch(es) of the converter can be turned on and off at zero-voltage (ZV); auxiliary switch of the proposed snubber cell can be turned on at zero-current (ZC) and turned off at ZV. There are no extra current and voltage stresses introduced on the main switch, and the reverse recovery current from the output diode is limited. The performance of the proposed active snubber circuit has been evaluated on a 2 kW, 180 V_in, 400 V_out interleaved boost converter. The peak efficiency of the converter is higher than 97.9%. Experimental results are in good agreement with the theoretical prediction.