Arpad, First, you have to think of the eye as a series of eye contours of probability that the eye will be inside that contour. Where the two horizontal lines you suggest cross each eye probability contour is essentially the bathtub curve. Walter Walter Katz 303.449-2308 Mobile 720.333-1107 wkatz@xxxxxxxxxx www.sisoft.com -----Original Message----- From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Muranyi, Arpad Sent: Wednesday, May 26, 2010 5:22 PM To: ibis-macro@xxxxxxxxxxxxx Subject: [ibis-macro] Re: Question about Receiver Sensitivity Thanks Mike and Walter for the explanation. This reminds me to another question I asked a while ago about eye templates. It seems that this sensitivity parameter could be interpreted as two horizontal lines across the eye diagram serving as if they were an eye template. The only difference is that it doesn't contain the timing component of the eye template, only the voltage or amplitude portion. Is my understanding correct? Arpad ====================================================== _____ From: Mike Steinberger [mailto:msteinb@xxxxxxxxxx] Sent: Wednesday, May 26, 2010 2:45 PM To: Muranyi, Arpad Cc: ibis-macro@xxxxxxxxxxxxx Subject: Re: [ibis-macro] Question about Receiver Sensitivity Arpad- The Rx_Receiver_Sensitivity is needed for the EDA tool to do an accurate job of estimating the bit error rate. Let me describe one of my favorite experiments. It's one my former group at Cray performed many times. 1. Take a signal directly out of a data generator and put it into a receiver. Measure the BER. - The BER should be indistinguishable from zero. 2. Using microwave attenuators, decrease the amplitude going into the receiver. Measure the BER. - Up to some attenatuation, the BER will remain zero. Then, with 1dB increase in attenuation, the BER will go from zero to 10e-3 or so. Anyone can perform this experiment with an eval board and a bag full of attenuators. It doesn't take a lot of time, skill, or money, and the same behavior will be observed for every SerDes on this planet, albeit with different minimum receive amplitudes. So, what happened in this experiment? The shape of the eye diagram remained the same (because microwave attenuators are nearly constant with frequency), but the amplitude decreased. At some minimum amplitude, the receiver stopped working even though the eye diagram (for example, as displayed on a sampling oscilloscope) is still absolutely beautiful. An EDA tool must be able to reproduce this experiment, and in order to do so accurately, it needs to know the Rx_Receiver_Sensitivity. The definition we currently have for Rx_Receiver_Sensitivity is exactly what we need and is successfully fulfilling the role it was originally intended for. Thanks. Mike S. On 05/26/2010 01:42 PM, Muranyi, Arpad wrote: Hello AMI experts, I know this was discussed before but it is still not clear to me how the Rx_Receiver_Sensitivity parameter is supposed to be used. This parameter is Type Info, meaning that it is not passed to the DLL, it is only information for the EDA tool. The question is, what is the tool supposed to do with this? I assume that if the DLL is written correctly, it would account for this sensitivity parameter in its algorithms (for example in CDR), so the EDA tool wouldn't need to adjust the returned times for the threshold (in)sensitivity. Is the EDA too expected to do anything with the returned waveforms when displaying eye diagrams and/or BER plots, etc...? If yes, what should be done? If no, what is the purpose of this parameter? Thanks, Arpad ============================================================= --------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/ IBIS Macro reflector: //www.freelists.org/list/ibis-macro To unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx <mailto:ibis-macro-request@xxxxxxxxxxxxx> Subject: unsubscribe