1 Reply Latest reply on Aug 7, 2015 11:12 AM by chris_balcom

    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:

      bulk of inductors.png

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

      bulk of inductors_2.png

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

      bulk of inductors_3.png

      bulk of inductors_4.png

       

      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

        • 1. Re: Why bulk of spiral insductors are connected to each other!
          chris_balcom

          Hi Majid,

           

          I don't have a clear idea why the connections are forming the way they are but I can offer a way to help troubleshoot the problem. Here's a link to a how-to video I made that shows some valuable techniques for finding exactly what material is on a certain net and highlighting different layers on that net one at a time. This can help provide insight. It helps us visualize the path that connectivity is taking from metal layers down through substrate or bulk or well and can help see unexpected connections between shapes.

           

          The key part of the technique for visualizing different layers on a net starts at 1:28 in the video:

           

           

          Please let us all know how it goes.