Performance Investigation of 2-GBaud QAMs Using Fully-Integrated SiGe Chipset at 240-GHz

This paper investigates the performance of quadrature-amplitude modulations (QAMs) of different orders with a 2 GBaud symbol rate over a wireless link in the 240 GHz band based on fully-integrated transmitter and receiver chips designed in a 130 nm SiGe technology. The results of end-to-end link measurements at 80 cm distance show the data rates of 4 to 12 Gbps, with an error vector magnitude (EVM) in the range of 7.5 - 8.5 % for all analyzed schemes. Targeting the bit-error-rate (BER) of 10-3, and using 2 GBaud symbol rate, the estimated maximal achievable distances based on the 240 GHz chipset are 3.7 m, 1.4 m, 0.9 m, and 0.7 m for 4-QAM, 16-QAM, 32-QAM, and 64-QAM, respectively. Furthermore, the paper discusses the prospects for throughput boost, using channel combining at an intermediate frequency (IF) as well as deploying Line-of-Sight multiple-input multiple-output (LOS-MIMO). By combining 5 channels and deploying 4×4 LOS-MIMO, depending on the used modulation scheme, data rates of 80 to 240 Gbps are conceivable.