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I dont know what your area constrant is and how crucial the matching is. But here is apossible solution:
D A C A C |A| C A C A D
D D D D D |B| D D D D D
D A C A C |C| C A C A D
D represents dummy and the y-axis of symmetry is where A B C reside (vertically) shown by | |.
There are many more solutions and hopefully this gives you an idea.
The solution proposed by cellphone (sorry cellphone) isn't good and have some clear mistakes.
It's better to increase a number of unity resistors, e.g. 18:2:18 or 36:4:36 (more elements = more precise matching). Matching pattern for example
DACCAACCAACCA|ACCAACCAACCAD
DACCAACBBCAACCA|ACCAACBBCAACCAD
DACCAACCAACCA|ACCAACCAACCAD
Don't forget about thermoelectrical effect at the resistor contacts. Number of resistors (A,B or C) must be even, and for two neibor resistors AA,BB,CC the direction of current flow must be opposite.
Good luck.
The solution proposed by cellphone (sorry cellphone) isn't good and have some clear mistakes.
It's better to increase a number of unity resistors, e.g. 18:2:18 or 36:4:36 (more elements = more precise matching). Matching pattern for example
DACCAACCAACCA|ACCAACCAACCAD
DACCAACBBCAACCAB|BACCAACBBCAACCAD
DACCAACCAACCA|ACCAACCAACCAD
Don't forget about thermoelectrical effect at the resistor contacts. Number of resistors (A,B or C) must be even, and for two neibor resistors AA,BB,CC the direction of current flow must be opposite.
Good luck.
The solution proposed by Denis is good, but for a small detail: dummies must be all around for they to be effective, as otherwise the central row sees a different surrounding than the upper an lower ones.
Hi Humungus. I'm really confuse because i have read a lot of books about analog circuit and layout design and have never seen such rule as "dummies must be around" resistor array. Can u provide reference?
From the viewpoint of mismatch introduced during manufacturing (e.g. during etching) that dummies gives nothing. Improvement of electrical surrounding I think is very ambiguous too.
Can anybody explain or arbitrate?
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