The Software Defined Radio (SDR) is a class of reprogrammable and reconfigurable radios which can be switched from one air-interface to another. It is generally employed in software, which can be easily realized on base-station side. On terminal-side, the configurability of the radio has to be maintained in hybrid architecture, consist of both software as well as hardware, due to computational cost of software solution and limited terminal capabilities. Keeping in view, the reconfigurability needs for SDR, this paper presents the design of reconfigurable Viterbi decoder suited for 3GPP, GSM and WLAN standards. Abstract-The Software Defined Radio (SDR) is a class of reprogrammable and reconfigurable radios which can be switched from one air-interface to another. It is generally employed in software, which can be easily realized on base-station side. On terminal-side, the configurability of the radio has to be maintained in hybrid architecture, consist of both software as well as hardware, due to computational cost of software solution and limited terminal capabilities. Keeping in view, the reconfigurability needs for SDR, this paper presents the design of reconfigurable Viterbi decoder suited for 3GPP, GSM and WLAN standards.