CALIBRATION OF OFFSETS IN TIME INTERLEAVED ADCS IN AN OFDM RECEIVER USING THE DIFFERENTIAL EVOLUTION ALGORITHM
M.V.N. Chakravarthi1, Dr. B. Chandramohan2
1Acharya Nagarjuna University, Nagarjuna Nagar-522510, India
2Bapatla Engineering College, Bapatla-522101, India
Keywords: Time interleaved ADC, differential evolution algorithm, orthogonal frequency division multiplexing (OFDM), bit error rate (BER)
Abstract
Time interleaved analog to digital converters (TIADCs) are used when high sampling rates are required. However, TIADCs have offsets such as the sampling time, gain, dc, and phase offsets. Due to these offsets, the reconstructed signal from TIADCs is erroneous. Hence, these offsets should be estimated and then corrected. The proposed work focuses on the estimation and correction of the offsets. For the estimation of offsets, the differential evolution optimization algorithm is used, and the correction is applied using the estimated offsets. The estimation is evaluated by finding the bit error rate (BER) and the signal to noise and distortion ratio (SNDR). The estimation and correction are implemented for 7 and 8-channel TIADCs in an orthogonal frequency division multiplexing (OFDM) system with 4-QPSK modulation. The technique is evaluated by applying monotonic sinusoidal and image signals to the OFDM system.
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