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What is the best resistor matching technique?

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diemilio

diemilio

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Hello everyone!!! I need to layout two resistors, one twice as large as the other. Which is the best matching technique to do this??

thanks for your help,

diemilio
 

Resistor matching

inter-digit
 

Re: Resistor matching

Hi
make one unit, which has length of GCD of two resistor lengths and do inter digitization with same orientation.
 

    diemilio

    diemilio

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Resistor matching

I would think of making three identical resistor, means, size, orientation, surrounding and etc all matched well. then using a strong metal to connect two of them in serial. now you have two resistors, one of them has twice the resistance value of the other.
 

    diemilio

    diemilio

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    V

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Re: Resistor matching

How about making 5 identical resistors and two of them should serve as dummy resistors on the sides.
 

Resistor matching

Good idear. I agree.
Using 5 identical resistors will work better.
 

Re: Resistor matching

Thanks everyone for your help.

I was wondering, if anyone has any references regarding this subject.

thanks again,

diemilio
 

Resistor matching

The fingers number decided by your resistors value and per_square value. Each finger is not too long(no reference data) or too short(lager than 10 square said in some paper).and add dummy in both sides of resisstors array. Array better use central symmetry.If the resistor are series, the top end and bottom end should bettere is near when use diffusion resistor in no_salicide process(reference 'the art of analog layout').
 

    diemilio

    diemilio

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Resistor matching

hi, you can find more detail answer in the book of The Art of Layout.
 

Re: Resistor matching

Hello everyone, thanks for all the posts.

What I'm looking for is info regarding resistor design taking into account power dissipation. I know how to calculate how long should a resistor be to get a specific resistive value (supposing W value), but what I need to know is how to select it's width so that the resistor works properly.

thanks for your help,

diemilio

ps: I didn't find this kind of info in any of these books:

Allan Hastings
Paul Allen
Franco Maloberti
 

Resistor matching

The various width's effect has been include in the good spice model. So you can check spice model in some founday's model. If this parameter is not in spice model, the resistor's width shoulld better lager than 3 times minima rules. If you need high resolution divide voltage, you need large width.Example poly resistor always larger than 2um in resistor-based ADC,DAC design in 0.35 technology.
Some foundry supply the device mismatch form, you can check this table, but always only transistors mismatch in this form.
 

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