Passive FIR filter design using reflections from stubs for high speed links

In the demand of multi-gigabit data transmission, finite-impulse response (FIR) filter as transmitter with de-emphasis has been extensively used to mitigate the inter-symbol interference (ISI) resulted from the skin effect and dielectric dispersion. In this paper, a passive FIR filter design is proposed to realize the de-emphasis performance by taking advantage of reflection under additional stub. A predictive method for received eye diagram performance, based on step response of interconnect system, is introduced to determine the optimal tap coefficients. The relation between the synthesized tap coefficient and the corresponding design variables [R_T1, Z₁, Z₂] is well established to facilitate the filter design. The proposed FIR filter design has the advantage of reducing the power consumption of the circuits and achieving eye diagram improvement efficiently.