Matching of resistor???

[vijay.kumarreddy]

which one matches better either low sheet resistor or high sheet resistor?
very urgent...

Thanks in advance
regards
vijay

 

[ppenday]

high sheet resistance matches better

 

[eng_Semi]

th only reason that the high sheet resistance matches better is that they will take small silicon area if compared to the low sheet resistance

 

[vijay.kumarreddy]

but as for as I know large area devices matches better.

 

[jcpu]

Hello Vijay

You are right.
Low sheet poly resistance generally matches better than high sheet poly resistance. Not because of larger area alone, but also due to the light implant concentration of high sheet resistance often fall close to intrinsic silicon whose resisitivity has exponetial relationship with the dopent and can vary a lot with little error in implant.

Best if you can find resistor matching report from foundry.
Most realistic data.

Have fun,

 

[vladimir1984]

polysilicon resitors with low sheet much better. 100% proved

 

[rfsystem]

The argument for high doping having better instrinsic matching is right. The difference is partly compensated by the higher relative impact of the contact resistance in low ohmic poly.

The best solution is to use circuit arangements where the performance does not depend on contact resistance at all. That boost matching by 2-3 which is equal to area reduction of 4-9.