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about the function of dbCreateParamInst

b0719r

Hi Everyone,

I am using the function of  dbCreateParamInst to draw a rf nmos with w, l, #f can be changed, however, when I use this function as below:

 paramList=list(list("wf" "float" fw) list("lf" "float" fl) list("nf" "int" nf))
    a=-(0.98*nf/4-0.2)
    b=-fw/2
   inst= dbCreateParamInst(newCV master nil a:b "R180" 1 paramList)

the mos size can not be changed, which seems as default size. I think the problem is the propName I use, it may be wrong. but I use this names before in the 90nm, it works ok, when I use them into 65nm, it doesn't work anymore. 

Is anyone have the idea that how to find the propName? or how to solve this problem?

  • Hi b0719r

    This is actually quite a common problem. There are generally 2 causes for it:

    a. Mismatch between property type in cdf and pcell codes. Please check if this is the cause. E.g. parameter "abc" is set to "float" in the pcell code but set as "string" in cdf.

    b. Need to trigger some pcell callbacks. This is harder to resolve and needs solution 11018344.


    Best regards
    Quek
  • Hi Quek, Thank you for your answer, you are right, the set in cdf is string, which is not suitable with my code, but I think if it is this problem, then it should shows error but not showing no error. The thing now is that when I check the properties of this nmos, the width per finger, length per finger, and the number of fingers has changed, but the total width is not( it is always the default value), and if I change one of these parameters, the total width changes immediately. Moreover, when I use different technology, such as umc90nm, it works ok, I also checked its type, which is also "string" while I define is as "float" in skill, it still works. do you have any idea about this situation? Thank you again for your answer! Best regards, Aleck

  •  Hi Quek,

    Thank you for answerming my question. I have checked the type thing, it is "string" in cdf, however, when I use umc90nm, the setting is the same, but it works for my code to use "float". So I think this is not problem. 

    Now my situation is that, when I check the nmos I drawed by this skill code,   I can see the parameters has been changed, but total width is not, which will be changed when I change parameters mannually. 

     Do you have any idea about this problem? 

     Best regards,

    Aleck

  •  Hi Quek,

     

    Thank you for answerming my question. I have checked the type thing, it is "string" in cdf, however, when I use umc90nm, the setting is the same, but it works for my code to use "float". So I think this is not problem. 

    Now my situation is that, when I check the nmos I drawed by this skill code,   I can see the parameters has been changed, but total width is not, which will be changed when I change parameters mannually. 

     Do you have any idea about this problem? 

     Best regards,

    Aleck

  • Hi Aleck

    Actually even though this is a common problem, it is a hard problem to resolve because it can possibly involve pcell callbacks and hence the pcell codes have to be examined. The COS solution which I had provided should be able to work for most cases. If it fails to work, it is better for you to file a service request to the local Cadence support so that somebody can assist you on this.

    Some pcells have a cyclic switch to control calculation of finger width or total width. This can sometimes break dbCreateParamInst. Hence we need to use the skillscript in the COS solution to force trigger all the callbacks. Sorry that actually I do not have much idea now on the cause of your problem. : )  Perhaps it might be a good idea to file a service request with us so that somebody can look into the issue.

    Best regards
    Quek

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