[petsc-users] floating region help

[Gong Ding]

On Tue, Sep 20, 2011 at 11:17, Gong Ding<gdiso at ustc.edu> wrote:
Thanks. Any recommends for solving this type of problems?
It's our bottleneck now.
Direct solver works, but not efficient for large 3D problem.
Krylov space based solver seems not rubost enough.
A more exact ILU preconditioner may help?
You can use domain decomposition with the jump aligned to subdomain boundaries. There are a variety of schemes with convergence rate independent of the jump, from both the overlapping Schwarz and Neumann-Neumann families.
Can you describe the 3D problem in more detail?
The problem arising from a CMOS inverter, or any CMOS gate.
For the inverter, there are PMOS and NMOS connected together.
When the PMOS and NMOS are both closed -- means nearly no current pass though the inverter.
the connection metal will see both huge resistance at VCC and GND end.  
 
  VCC                  connection metal                      GND
 ____    PGate        _____________________     NGate       _____
    | ____________   |                    |  ____________  |
  __|________________|__                __|________________|__
   P  |           | PSource           NDrain |            | N
  -----           -----                  -----            -----
          NSub                                    PSub
In fact, I had already add some leakage current to the inverter -- can not be more due to accurate limit.
The conductance of metal still 1e6~1e10 times larger than "effective" conductance in the NMOS and PMOS.
Can anyone give some detailed suggestion?
Thanks.
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