Enhanced passive equaliser using open-stub structure

An open-stub compensation technique is proposed for passive equalisers used in high-speed digital communication systems. By simply lumping an open stub to the conventional RL-type passive equaliser, the frequency-dependent channel loss from the long transmission path can be compensated, the frequency response of the channel becomes more flat and the bandwidth is wider. On comparing the proposed passive equaliser with typical RL passive equalisers, the simulation results show that the proposed technique can achieve an improvement by 1 GHz in the flat region of S21 on a 60 cm-long differential pair. Thus, the proposed technique successfully demonstrates an improvement in electrical performance of about 57.4% in the time domain.