FPGA Prototype for WLAN OFDM Baseband with STPE of I/Q Mismatch Self Calibration Algorithm

Based on the single tone power evaluation (STPE), a self-calibration algorithm of I/Q mismatch is proposed for the IEEE 802.11a WLAN systems. The self-calibration algorithm is performed by the digital baseband at transceiver start-up to measure the signal power of the single tone signal, which is located at the double frequency band at the receiver. Furthermore, the residual I/Q mismatch is tracked during the physical data transmission. Therefore, the design requirements of the RF front-end for the WLAN OFDM transceiver are alleviated. According to the proposed algorithm, the residual signal-to-noise ratio (SNR) degradation is totally less than 0.5-dB with plusmn5% gain mismatch (DeltaG) and plusmn5deg phase mismatch (Deltathetas) in the transmitter and receiver respectively, and carrier frequency offset (CFO = plusmn232kHz). Finally, the prototype of the IEEE 802.11a WLAN baseband is realized by the Altera Stratix EP1S80 DSP development board with about 32000 logic elements at 40MHz