Time-Interleaved ADC Gain Mismatch Calibration in High-Speed OFDM Systems

Abstract

Rapid growth in high-speed communication technologies nowadays has led to the latest development and implementation of 5G and beyond globally thanks to the use of orthogonal frequency division multiplexing (OFDM) technique. However, such high-speed OFDM-based systems cannot function properly without massive tuning in several parts such as the use of time-interleaved analog-to-digital converter (TI-ADC) at the receivers in order to match with extremely high sampling rates while keeping affordable costs. A TI-ADC, in turn, poses many risks of deficiency to its processed data when not calibrated appropriately, mostly due to mismatches between sub-ADCs in a TI-ADC such as offset, gain and timing mismatches, which can significantly degrade an overall system performance. In this paper, we focus on gain mismatch. We propose a simple and efficient method to calibrate the gain mismatch based on the least-square (LS) algorithm assuming an AWGN channel. The simulation results show that our method is capable of significantly improving the bit error rate (BER) performance of OFDM systems.