10.6.2 Matched pair layout guidelines¶
Sr.No |
Guideline |
Comment |
MP.1 |
Matched pair device layout shall be exactly identical to each other (as shown in above diagrams) |
|
MP.2a |
Matched pair devices shall be of the same dimension. If the matching is required to be 1:n ratio, then a unit cell of the same size shall be used. |
|
MP.2b |
For matching requirement of 1:n ratio for transistors, following layout shall be avoided: Expecting 1 finger device to have “n X” ratio matching with “n” fingers (n>=2) devices. Expecting one of the fingers of n finger transistor to be have (1: “n-1”) ratio matched with its rest of (n-1) finger. (n >= 3) |
|
MP.3 |
Matched pair devices shall be placed as close as possible to each other (of course abiding by layout rules) |
|
MP.4 |
Matched pair devices shall preferably be surrounded by one row of identical dummy devices. |
|
MP.5 |
Matched pair devices shall see identical surrounding around it. For example if two NMOS in P-substrate are expected to be matched and one of them have Nwell adjacent to it and other have P-substrate tap their matching will not be good. |
|
MP.6 |
Metal connection width and lengths to each identical node of the matched pair shall be similar |
|
MP.7 |
Matched pair devices shall run in parallel and not in perpendicular or anti Parallel. |
|
MP.8 |
Use cross-coupled or interleave kind of layout to create as much symmetry in the devices as possible (see examples of matched pair layouts) |
|
MP.9 |
Do not use smallest design rule lines and widths. Minimum device dimensions (L and W) used for matched pair shall be 2 or 3X to the minimum design rules in that technology for those devices. |
|
MP.10 |
There shall not be any unrelated (not as a direct part of the device or its direct connection) conductors (metal, poly or salicided diffusion), over or under the matched pair devices. |
|
MP.11 |
Matched pair devices shall not be separated by unrelated devices in Between. |
|
MP.12 |
Matched pair devices shall see identical DC bias at all identical device Nodes. |
|
MP.13 |
Matched pair devices shall have same well (either both Nwell or both Pwell) underneath. |
Note
10.6.2 Matched pair layout guidelines Appendix B: Rules not coded
