A 4×4 multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modem with onesymbol-locked timing recovery, anti-I/Q mismatch frequency recovery, frequency-dependent I/Q mismatch estimation and adaptive equalization is implemented in 0.13-m CMOS library. This chip occupies 4.6×4.6 mm 2 and consumes 62.8 mW at 1.2 V.I.
This work presents a novel carrier frequency offset (CFO) estimation algorithm, based on pseudo-CFO (P-CFO), to estimate the CFO value under the conditions of I/Q mismatch for direct conversion structures with 2-dB gain error and 20-deg. phase error in frequency selective fading channels. To circumvent CFO with I/Q mismatch, the proposed P-CFO algorithm rotates three training symbols by adding extra frequency offset into the received sequence to improve CFO estimation. Simulation results indicate that the estimation error of the proposed method is about 0.3 ppm, which is lower than those of two-repeat preamble-based methods. Additionally, the proposed P-CFO algorithm is compatible with the conventional method, and is appropriate for SoC implementation. The proposed scheme is implemented as part of an orthogonal frequency-division multiplexing wireless receiver fabricated in a 0.13-m CMOS process with 3.3 0.4 mm 2 core area and 10-mW power consumption at 54-Mbits/s data rate.Index Terms-Carrier frequency offset (CFO), direct conversion, I/Q mismatch, orthogonal frequency-division multiplexing (OFDM).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.