Signal Quality Impairments By Analog Frontend Non-Idealities In A 300 Ghz Wireless Link

This paper discusses the influence of nonidealities in the analog transmit and receive frontend of an MMIC-based 300 GHz wireless link on the receive signal quality. The degradation of EVM due to limited bandwidth and gain imbalance in the quadrature up-and down-converters is considered and compared to experimentally achieved data. Using adaptive equalization and quadrature error correction in the digital baseband, the measured EVM in a 1 m data transmission is improved by up to 4.5 dB from its raw value and stays below -12.75 dB for data rates of up to 36 Gbit/s with QPSK modulation. A frequency dependent theoretical analysis of quadrature gain imbalance allows to derive its impact on receiver EVM as a function of baud rate.