Eye opening center

Dear Kadian,

I am not aware of a specific calculator function to locate the maximum eye height (something analagous to eyeAperture). But, perhaps a simple linear sweep in an ocean script might accomplish what you want. You might consider something like this ocean script that you can run from the command line or CIW. I usually use the file extension ".ocn" for ocean scripts, but the Forum requires me to use ".txt" in order to upload the file. Hence, if you care to try the script, you might consider changing its extension from ".txt" to ".ocn". You may invoke it from the command line in your working directory as:

ocean -nograph < eye_hieght_sweep_052523v1p0.ocn > run.out

or from the CIW:

load( "eye_hieght_sweep_052523v1p0.ocn")

Shawn

---------------------------------------------------

simulator('spectre)

PERIOD = <your_clock_period_for_NRZ_data>
TSTART = <start_time_for_eye_diagram_analysis>
TSTART = <stop_time_for_eye_diagram_analysis>
vthreshold = <your desired threshold voltage>

simulator_results = strcat("<path_to_your_results_directory")

eye_waveform = eyeDiagram(v("vout" ?result "tran-tran" ?resultsDir simulator_results) TSTART TSTOP 2*PERIOD ?autoCenter t )

sprintf(fname_csv "eye_height_measurements.csv")
fp = outfile(fname_csv "w")
fprintf(fp "Time (sec),Eye height (V)\n")

delta_t = PERIOD/10.0
time = 0.50*PERIOD
max_eye_height = -1.0
max_eye_height_time = 0.0

while(time < (1.50*PERIOD + 0.10*delta_t)

eye_height = eyeHeightAtXY(eye_waveform time vthreshold ?output "total")
fprintf(fp "%1.6e,%1.6e\n" time eye_height)

if( (eye_height > max_eye_height) then
	max_eye_height = eye_height
	max_eye_height_time = time
	)
time = time + delta_t) ; end while loop

fprintf(fp "Maximum eye height of %1.6e V at %1.6e s\n" max_eye_height max_eye_height_time)
close(fp)

exit()

---------------------------------------------------

Dear Shawn, 

Thanks for the reply. That helps a lot. I also had written similar code and tried to invoke the script from the ADE explorer window. But unable to do that.  I was able to get the center location using the same script when I loaded through CIW. Error window is showing that the definition of output might be not correct. (For calling the ocean script from the ADE explorer followed the steps shown in this How do I use an OCEAN measure script in ADE Explorer, Assembler, or ADE XL? (cadence.com))

Kadian

Dear Shawn, 

Thanks for the reply. That helps a lot. I also had written similar code and tried to invoke the script from the ADE explorer window. But unable to do that.  I was able to get the center location using the same script when I loaded through CIW. Error window is showing that the definition of output might be not correct. (For calling the ocean script from the ADE explorer followed the steps shown in this How do I use an OCEAN measure script in ADE Explorer, Assembler, or ADE XL? (cadence.com))

Kadian

Kadian,

The most likely reason is that the script doesn't handle family data - so it is quite likely to fail if run on the entire set of data (or you use re-evaluation). I think you'd have to write this as a new function:

procedure(CCFfindMaxEyeHeightTime(eyeWaveform vthreshold startTime stopTime delta_t)
  cond(
    (drIsWaveform(eyeWaveform)
      let((time eye_height (max_eye_height -1.0) (max_eye_height_time 0.0))
        time=startTime
        while(time < (stopTime + 0.10*delta_t)
          eye_height = eyeHeightAtXY(eyeWaveform time vthreshold ?output "total")
          ;printf("%1.6e,%1.6e\n" time eye_height)
          when( eye_height > max_eye_height
            max_eye_height = eye_height
            max_eye_height_time = time
          )
          time = time + delta_t
        ) ; end while loop
        max_eye_height_time
      ))
    (famIsFamily(eyeWaveform)
      famMap('CCFfindMaxEyeHeightTime eyeWaveform vthreshold startTime
        stopTime delta_t
      )
    )
    (t
      error("CCFfindMaxEyeHeightTime: cannot handle %L\n" eyeWaveform)
    )
  )
)

Note, I have not tested this code. You'd call it from the outputs using something like:

CCFfindMaxEyeHeightTime(eyeWaveform threshold PERIOD*0.5 PERIOD*1.5 PERIOD/10.0)

The first argument is the output of an eyeDiagram.

Andrew

Hi Andrew,

Thanks for the repIy. I tried loading the above script from the CIW and used the function in the Outputs pane in the ADE explorer window. Was able to get the max eyeheight point. Can I include the ocean script in the ADE explorer window itself instead of loading from the CIW.

Kadian

Hi Kadian,

Glad it worked (not bad, since I didn't test it!) You have two approaches you could take:

1. You could add this function as a new function in the calculator; either use the "fx" button in the function panel in the calculator, or the "+" button in the Expression Builder in ADE Explorer/Assembler. Define the UI and save back to the file - this will then cause it to be automatically loaded at startup and then be available in the calculator. This is the approach I'd use
2. Load the file from your .cdsinit (and .vdsinit it using LSCS).

That's cleaner than adding the function in an OCEAN script measurement which would cause the function to keep being redefined.

Andrew