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Why bulk of spiral insductors are connected to each other!

Majid Rafei

I have drawn a layout consisting 8 spiral inductors in Virtuoso. I also have used 130 nm TSMC. In the design, I have connected the bulk of spiral inductors to ground pin using RF-poly-resistors (a resistor for each inductor). When I run LVS by calibre, It says that bulk net of 7 of spiral inductors are connected to each other, but physically, I have not connected bulk of spiral inductors to each other!

You can see the Mentor Calibre error in the below image:

I also have similar errors with the bulk of spiral inductors, Calibre is not able to find bulk net of spiral inductors. I have attached another image shows this:

I have uploaded two more images which show how bulk of spiral inductors are connected to the ground pin using RF-poly-resistors:

What is the issue with the layout? How can I overcome this problem?

Hint: I have tested a simple design with two MOSFETs and two spiral inductors (using 130 nm TSMC and calibre), and I have no problem like this!

Software Versions: IC614, Calibre 2011.2

  • This could be a problem with your Calibre deck not recognizing the bulk pin on the inductors or it is misinterpreting the resistor. Try connecting two MOSFETS bulk with the resistors and run through Calibre.

  • Dear theopaone,

    Thanks for your attention.

    I have done as you suggested. You can see the layout of two transistors which bulks are connected using a resistor:

    As can be seen, Calibre does recognize the bulk of MOSFETs and the LVS is done completely.

    Any other suggestions are welcome.

  • I have done another test which in addition of MOSFETs and resistors, contains spiral inductors. The earliest problem is again remained. I think that, as you mentioned too, the bulk of spiral inductors is not recognized by Calibre.

    I should mention that I have converted my technology files from CDB to OA. What can I do to fix the problem?

  • The problem is probably in the Calibre deck. It may not be recognizing the bulk pin on the inductor. You would have to engage a Calibre expert or go back to the deck supplier and have them fix the problem.

    Ted

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