Learning Forum

[Juliana.mueller]

Hi,

I have a problem to get reliable Q-factor results for my optical link. I assume it's due to the fact that my Interconnect simulation only simulates 1 PRBS cycle and it's not enough data to reliably calculate the Q-factor. I couldn't find the option to simualte more than 1 cycle, how do I do that?

[Guilin Sun]

If you want to calculate Q factor from transmission you do not need PRBS signal, as you need the steady state simulation in frequency domain. Please refer this example https://optics.ansys.com/hc/en-us/articles/360042323794-Ring-resonator-using-INTERCONNECT-primitive-elements 

One you get the transmission you can extract data and calculate Q from f/dleta_f where delta_f is the width of a resonance peak at f.

PRBS is for time domain simulation.

[Juliana.mueller]

Thank you for your reply. I believe I wasn't clear enough. I want to extract the signal quality factor (Q=(P1-P0)/(sigma1+sigma0) )from the eye diagrams. I could also extract the BER.

I think I simply need to get rid of the inheritance of the PRBS order from the root element. But I haven't figured out how to do that yet. I can change from which parameter it inherits, but not simply delete the inheritance from anything. My goal ist to run a time domain simulation and to simulate several PRBS cycles. I hope that this would improve the statistics of the signal and that the calculation of the signal quality factor or BER results in the same value for each simulation. Right now it changes by an order of magnitude for the same optical link .

[Guilin Sun]

Ok, this is clear for me.

I think you can increase the number of pulses. The following links might be helpful:

https://optics.ansys.com/hc/en-us/articles/360036618013-PRBS-Generator-PRBS-INTERCONNECT-Element

https://optics.ansys.com/hc/en-us/articles/360036736813-Root-Element-ROOT-INTERCONNECT-Element

https://optics.ansys.com/hc/en-us/articles/360045467653-Time-Domain-Simulations-Introduction-to-INTERCONNECT-Time-Domain-Simulations-Demo

%bitrate% is the bitrate inherited from the root element. If you want to manually specify a value that is not dependent on the bitrate, you would need to remove this expression. 

You can see the bitrate is calculated as 0.75*%bitrate%, where %bitrate% is the bitrate inherited from the root element. the “bitrate” in Root Element is the symbol rate, and please modify the “bitrate” in the PRBS based on the modulation format for correct bitrate. 

You can probably find more information about PRBS and eye disgram in the KB website.