Hi Joel: The emphasis greatly affects the jitter ,but spice models usually don't include it.So,I think it is valueless to simulate jitter using spice model.the measuring data is believable. --- Original Message --- From: "Joel Brown" <joel@xxxxxxxxxx> Sent: February 13, 2015 8:26 AM To: "SI-List" <si-list@xxxxxxxxxxxxx> Subject: [SI-LIST] Question about jitter at serdes transmitter We are using an Altera Arria II GX FPGA for a SATA 3 6GBPS interface. I ran some simulations in Hspice and the amount of jitter in the simulation is much less than what I measured on the actual system. I decided to simplify the system by isolating the board with just the FPGA on it and terminating the trace with a 100 ohm 0201 resistor. The differential trace is about 1.5 inches long and runs on a single surface layer. My simulation shows about 1.6 db loss at 3 GHz which is about what I am measuring on the scope. When I look at the output of the FPGA I already see about 32 ps of jitter (0.2 UI) and it seems to be data pattern related. Is this a normal amount of jitter to expect at the output of a serdes transmitter? In the actual system the signal runs across five boards and four connectors before arriving at a redriver and by then its pretty hosed. The simulated loss is about 9 db. Thanks - Joel ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu