FIR filter optimization as preemphasis of high-speed backplane data transmission

FIR filter preemphasis has been used to counteract intersymbol interference (ISI) in high-speed backplane data transmission. Backplane channel characteristics are first analyzed. It is found that channel group delay distortion is also a major ISI contributor in addition to amplitude attenuation. A MATLAB program is then described for optimization of the FIR filter under the LMS criterion. Both symbol-spaced FIR (SSF) and fractionally-spaced FIR (FSF) are comparatively studied at different data rates. The determination of tap number and preference of FSF to SSF are discussed.