[SOLVED] cancelling the process variation effect of 50ohm resistor

[a1s7trea]

Dear All,

I was wondering if there is a way to cancel the effects of the process variation to the value of a termination resistor of 50ohm as this value can very easy go up or downb by approx. 20%


many thanks

Nik

 

[oermens]

Re: cancelling the process variation effect of 50ohm resisto

increasing nf, W, L, can reduce sensitivity to process. if area permits use many long and wide resistors in parallel whose equivalent resistance is 50ohm.

 

[a1s7trea]

Re: cancelling the process variation effect of 50ohm resisto

Thank you

Regards

Nik

 

[love_analog]

I am not sure I agree with oermens. Yes, those things help in matching between resistors but 20% is still there just because of process shifts. The only way to really reduce this is to calibrate to a known external resistor

 

[upvl]

Re: cancelling the process variation effect of 50ohm resisto

Dear All,

I was wondering if there is a way to cancel the effects of the process variation to the value of a termination resistor of 50ohm as this value can very easy go up or downb by approx. 20%


many thanks

Nik

The foundry will tell you the resistance will vary up to 20% in different technology corners and temperatures. But, actually, the variance won't be so much according to my experience. It's generally about 5% in some mainstream processes, and you can increase the size to get a better performance.
However, different foundries will have different technology, you'll have to be more careful if you use the foundry for the first time.