Analog Crosstalk Cancellation for High Data Rate Communication Links

In this work, a design of an analog I/Q crosstalk compensation circuit in 130 nm SiGe BiCMOS is proposed. The circuit consists of four baseband variable gain amplifiers based on Gilbert cells. As a proof of concept, a 20 Gbps QPSK input signal with high bidirectional crosstalk (20% and 30 %), equal to an error vector magnitude (EVM) of 25.1 % and signal-to-noise ratio (SNR) of 12.0 dB, was improved to EVM=16.1 % and SNR= 15.9 dB at the output. Unidirectional cross-talk up to 50%, was investigated, and at 50 % the EVM improved from 25.9 % to 18.6 %, and the SNR from 11.7 to 14.6 dB.