Applications using high data rate drives the need of spectrally efficient and high-throughput broadband systems. Cognitive radio is the persuasive solution to the spectral crowding problem that allows wireless networks to sense the surroundings, adjust and learn from previous knowledge to obtain better communication. Orthogonal Frequency Division Multiplexing (OFDM) is adapted as the best transmission method for current and future wireless communication systems. Spectrum sensing helps in identifying underutilized band to provide better spectral resolution. The efficiency of the cognitive radio relies on the speed and accuracy of spectrum sensing. The ultimate aim of an OFDM-Cognitive radio is to improve utilization of spectrum and to provide consistent communication for all users in a cost-effective manner. In this study, spectrum sensing unit is designed and the architecture for OFDM based transmitter is developed and implemented in Field Programmable Gate Array (FPGA), family Virtex 5, device XC5VLX50.