{"id":288685,"date":"2023-06-14T11:11:54","date_gmt":"2023-06-14T11:11:54","guid":{"rendered":"\/forum\/forums\/topic\/ideal-50-ohm-transmision-line-ringing-while-performing-tdr-in-siwave\/"},"modified":"2023-06-14T11:13:03","modified_gmt":"2023-06-14T11:13:03","slug":"ideal-50-ohm-transmision-line-ringing-while-performing-tdr-in-siwave","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ideal-50-ohm-transmision-line-ringing-while-performing-tdr-in-siwave\/","title":{"rendered":"“Ideal” 50 ohm transmision line ringing while performing TDR in SIwave"},"content":{"rendered":"

Hello,<\/p>\n

I have been trying to simulate TDR of the “Ideal” 50Ohm line (50-ohm source, line, and termination).<\/p>\n

Schematic:++<\/p>\n

<\/p>\n

PCB:
<\/p>\n

The thickness for 50R has been calculated via Altium’s integrated 2D solver to be 0.325mm. The total delay of the trace is around 662ps:<\/p>\n

<\/p>\n

Once I simulate TDR with SIwave’s integrated TDRwizard I get this as a response:<\/p>\n

<\/p>\n

I understand the first dip to ~9.5 ohm is due to the simulation starting and the current not instantaneously becoming the I=U\/Z but rather “ramping up” to that value. But I don’t understand why there is a ringing afterward. Shouldn’t the response be a flat line if everything is matched correctly and not swinging +-3 ohms? Do you maybe know why this is the case? Is it typical for simulation or do you think that I am doing something wrong?<\/p>\n

For any further clarification please don’t hesitate to ask.
Marin <\/p>\n

 <\/p>\n","protected":false},"template":"","class_list":["post-288685","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t