DC wander is something I'm worrying about.
One question is that 8B10B coding is defined as DC balanced. However, it is hard to define the low end of spectrual content.
By the way, what is the definition of brutto baud rate?
rf-design wrote on Jul 11th, 2009, 1:01am:I did not remember it exactly but I guess the lower corner is 1/8 of the brutto baudrate. The design approach is to limit the DC-wander. So each of the 256 codes have a specific DC content. You can interprete the high pass filter as a integrator as feedback element. So a long sequence of symbols which have the highest number of ones or zeros change the DC-value of the feedback integrator. The DC-value reduce the useable eye-size. So independend of the integrator value a long sequence of the critical symbol will set the limit.