I am trying to answer the question - Does a signal's rise time increase with the length of a lossless transmission line? - using LTspice simulation. Some references say that lossless transmission line does not degrade the signal. Does it mean the rise time remains the same? Intuitively, it seems to me that the rise time should increase as the length increases.
I tried two cases. Case-1 is with LTspice T-Line model and Case-2 is with distributed LC model. In each case, I simulated with four cascaded T-Line models, each having 250ps delay, to give a total of 1ns delay. In Case-2, each "T_100" component has 100 LC segments (L = 0.125nH and C = 0.05pF). Rise time was set to 10ps.
Case-1 results in signal being delayed by 250ps per T-line with no appreciable change in rise time. While Case-2 results in significant increase in rise time along with 250ps delay per T-line.
I can't seem to figure out which one is correct. Attached are the LTspice schematics I used.