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How to pass parameter to "number of pair of points, time, voltage" parameters of cell "vpwl" inside a pcell?

Yuto Lau

Hi everyone,

I would like to add some features on Andrew's bussetp.il script, (the script is in this link: https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000nX1lEAE&pageName=ArticleContent.).

(previous post: https://community.cadence.com/cadence_technology_forums/f/custom-ic-skill/65168/how-to-pass-parameters-to-sub-cells-parameter-in-pcell),

I want to add cell "vpwl" from analogLib into pcell "bussetp". Besides defining "vhi" and "vlo" as parameter "vdc" of "vpwl" as in previous post (https://community.cadence.com/cadence_technology_forums/f/custom-ic-skill/65168/how-to-pass-parameters-to-sub-cells-parameter-in-pcell), 

I try to pass parameter to "number of pairs of points", "time X" and "Voltage X" (X is determined by value of "number of pair"). With this feature, I can define the control signal waveform in transient sim, like power on sequence.

However, I encounter two issues as below

1) For cell "pwl" , the value of "Time" and "Voltage" are combined as a vector, passing to parameter "wave". How can I realize such combination?  

2)  As number of "Time" and "Voltage" pair is unknow until "number of pairs of points" is defined, how should I define pcell CDF so that it can adjust the number of inputs?

Could you please give me any idea or point me to some useful material?

Thanks and regards,

Yutao

  • Yuto Lau

    Hi everyone,

    My above question maybe unclear.

    Let me make the question into small section and in detail.

    In below script, I would like to dynamically assign pcell parameter (time1, time2...) to instance field (t1, t2,...), based on value of "tvpairs".

    However, concat("t" i) return a string instead of variable.

    Do you know any way to convert a string to field name? Or any way to edit instance field in an iteration loop?


    vpwlMaster = dbOpenCellViewByType("analogLib" "vpwl" "symbol" nil "r")
    ;----------------------------------------------------------------
    ;Create vdc instances for hi and lo
    ;----------------------------------------------------------------
    vhiInst = dbCreateInst(cv vpwlMaster "VHI_SRC" -1:0 "R0")
    vloInst = dbCreateInst(cv vpwlMaster "VLO_SRC" -1:-0.5 "R0")

    ;; Set number of time-voltage pairs
    vhiInst->tvpairs = pairs
    vloInst->tvpairs = pairs

    ;; Dynamically assign t1..tN and v1..vN
    for(i 1 pairs
    vhiInst->concat("t" i) = sprintf(nil "pPar(\"time%d\")" i)
    vhiInst->concat("v" i) = sprintf(nil "pPar(\"vh%d\")" i)
    vloInst->concat("t" i) = sprintf(nil "pPar(\"t%d\")" i)
    vloInst->concat("v" i) = sprintf(nil "pPar(\"vl%d\")" i)
    );for

    Thanks and regards,

    Yutao

  • henker
    in reply to Yuto Lau


    You would use dbCreateProp to set properties on the instance:
    dbCreateProp(inst propName propType propValue)

    e.g.
    ;; Set number of time-voltage pairs
    dbCreateProp(vhiInst "tvpairs" "int" pairs)
    dbCreateProp(vloInst "tvpairs" "int" pairs)

    or

    ;; Dynamically assign t1..tN and v1..vN
    for(i 1 pairs
      dbCreateProp(vhiInst sprintf(nil "t%L" i) "string" <time as string, e.g. from pcell formal parameters t[i]>)
      dbCreateProp(vloInst sprintf(nil "v%L" i) "string" <voltage as string, e.g. calculated per time point and bit>)
      ...

    To convert a string to a symbol use 'stringToSymbol'

    Regards,

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