A current mode driver can be designed to operate in Class A only. Such a driver only has to pull down (or up) by a varying degree to represent the drive level desired at a given moment. A voltage mode driver has to pull up and/or down to each output level. Multiple transistors must turn and off to effect a change from one output drive level to another. From an SI standpoint it is easier for a chip designer to get a high degree of symmetry between the two lines of the pair using current mode. As a board designer you don't care how hard or easy the chip design is. You care about what the chip delivers at the package / PCB interface. Steve On 5/2/2014 12:14 AM, vinod ah wrote: > Hi All, > I have a basic query on usage of current waveform or voltage waveform for > transmission of signals from Serdes driver to receiver over PCB channel. > > I understand that from a chip driver design point of view, current output > is preferred. > > But i am trying to understand what benefits do we get from Signal integrity > (from board design aspect we do get benefit of no did/dt issues) point of > view if we transmit a current waveform over the channel (which ultimately > gets converted to voltage at Rx termination) compared to voltage waveform. > > I did read some articles on web which say current waveforms are more > resistant to interference/noise, not sure why is it so....... > > Regards > Vinod A H > > > ------------------------------------------------------------------ > 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 > > > -- Steve Weir IPBLOX, LLC 1580 Grand Point Way MS 34689 Reno, NV 89523-9998 www.ipblox.com (775) 299-4236 Business (866) 675-4630 Toll-free (707) 780-1951 Fax All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved. This e-mail may contain confidential material. If you are not the intended recipient, please destroy all records and notify the sender. ------------------------------------------------------------------ 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