Routing Halo?

Hi Rahul,

Routing Halos (created with "addRoutingHalo" or via the GUI) are used to discourage the signal router from creating long parallel routes adjacent to hard macros in the design. This is often desired because of the uncertainty associated with the routing patterns inside the hardened object. There could be long parallel runs near the perimiter *within* the hardened object so to avoid a possible signal integrity problem Routing Halos can be used to discourage long parallel runs near the edge of hard macros to which they are applied.

Without such a construct, users might attempt to use hard routing blockages (created with "createRouteBlk") instead of halos. The problem with this approach is that hard routing blockages prevent *all* routing from going near the block which makes pin access problematic and creates DRC violation markers. Further, routing halos are easy to create because they are attached to hard macros and move along with the hard macro if the hard macro is moved. Routing Halos are therefore preferred for this purpose.

It's worth noting explicity that a routing halo is *not* identical to a hard routing blockage created on top of a hard macro. A hard routing blockage created on top of a hard macro would prohibit signal and power routing from entering anywhere within the hard routing blockage whereas a routing halo is only applicable to signal routes adjacent to the perimeter of the hard macro it is associated with.

You can find more information about Routing Halos in the Encounter Text Command Reference, shipped with the software and available on Sourcelink here:

http://sourcelink.cadence.com/docs/files/Release_Info/Docs/fetxtcmdref/fetxtcmdref8.1/floorplanT.html#1258686

Hope this is helpful,
Bob

Hi Rahul,

Routing Halos (created with "addRoutingHalo" or via the GUI) are used to discourage the signal router from creating long parallel routes adjacent to hard macros in the design. This is often desired because of the uncertainty associated with the routing patterns inside the hardened object. There could be long parallel runs near the perimiter *within* the hardened object so to avoid a possible signal integrity problem Routing Halos can be used to discourage long parallel runs near the edge of hard macros to which they are applied.

Without such a construct, users might attempt to use hard routing blockages (created with "createRouteBlk") instead of halos. The problem with this approach is that hard routing blockages prevent *all* routing from going near the block which makes pin access problematic and creates DRC violation markers. Further, routing halos are easy to create because they are attached to hard macros and move along with the hard macro if the hard macro is moved. Routing Halos are therefore preferred for this purpose.

It's worth noting explicity that a routing halo is *not* identical to a hard routing blockage created on top of a hard macro. A hard routing blockage created on top of a hard macro would prohibit signal and power routing from entering anywhere within the hard routing blockage whereas a routing halo is only applicable to signal routes adjacent to the perimeter of the hard macro it is associated with.

You can find more information about Routing Halos in the Encounter Text Command Reference, shipped with the software and available on Sourcelink here:

http://sourcelink.cadence.com/docs/files/Release_Info/Docs/fetxtcmdref/fetxtcmdref8.1/floorplanT.html#1258686

Hope this is helpful,
Bob