Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

When should I use Dummy Transistors?

Status
Not open for further replies.

ryusgnal

Advanced Member level 4
Full Member level 1
Joined
Oct 4, 2005
Messages
102
Helped
3
Reputation
6
Reaction score
1
Trophy points
1,298
Location
Malaysia
Activity points
1,992
when should i apply this?

43_1172651470.JPG


is it only for even number of fingers or should apply everytime we use multifinger? Help please....
 

dummy transistor layout

Hi,
To minimize the etch effects during fabrication. If they are not placed then it can so happen that one side is slightly more parameter(Vth e.g) then the other transistor. Hence the matching will not be identical for all the devices. For a good matched layout dummy devices must be used. Generally dummy devices are added to resistors as well so that they surround the complete resistor.
BR
Vabzter
 

dummy transistors

is it only for even number of fingers or should apply everytime we use multifinger? Help please....[/quote]

The dummy structure is not only for even fingers, but also for odd fingers or you think you should use the dummy for immunity orther fabrication influence:diffusion imp and so on.
I think you can get two mirrors. and take the two mirrors under the sun. You should see the different between the mirrors and the sides of the mirrors.
If you want to get the same shallow, i think you can take more mirrors, maybe 4. and take the four mirrors under the sun, you can get the same shallow. The trasnsitor is the same while fabrication.
Or, you can info for a process engineer. The above is my opion.

I think the dummy is not only use for immunity fabrication, maybe some other surroundings we can use.

And the more fundamental about dummy, you can refer to <<The Art of Ananlog Layout>> or other books.

Best wishes for you
 

transistors for dummies

If I put dummy transistor in my layout, is it will effect my LVS (Layout Versus Schematic) Result?
 

dummy poly structure

ryusgnal said:
If I put dummy transistor in my layout, is it will effect my LVS (Layout Versus Schematic) Result?
hi,
yes, i think it will take effect, so you should add the dummy tansistor in the schemetic.
goo luck
jeff
 

transistor for dummy

Dummy poly alone is enough no need for the dummy transistor.
 

dummy poly

This dummy transistor layout is better than just putting poly without diffusion.
This is a typical dummy layout for those RF design or highly sensitve analog layout design. Just putting poly will have profile not flatten around the edge as the diffusion is already missed out there, so therefore, don't be lazy to put a real dummy transistor at both ends. This is a practical situation that I have saw it from some layout designers working over 20 years in the field.

Also, dummy is added whenever you feel comfortable from design point of view and you need to add dummy transistors in the schematic to make LVS passed.

Dummies are much required when your transistor's device size is very small, tending to have more rupture effect during fabrication.
 
  • Like
Reactions: ayanbur

    ryusgnal

    Points: 2
    Helpful Answer Positive Rating

    ayanbur

    Points: 2
    Helpful Answer Positive Rating
How can I add dummy transistor to schematic even layout?
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top