MOSFET mismatch in the differential pairs

[midgariano]

Hello Everybody.

I need some imformation about the mismatch of the mosfet transistors, especially about this phenomenon in the differencial pairs. I was seeking this topic but I haven't found any information.
I really need that.

Thank's a lot.

 

[jecyhale]

mosfet mismatch

Firstly, Use large area MOSFET.
Sencondly, divide the MOS into two parts, and cross connect them.
Thirdly, add some dummy MOS around them.

 

[spring1860]

mosfet mismatch

hi
maybe this doc helped you


BR

 

[engrak]

Mosfet Mismatch

plz read allen hasting book.

 

[lvlei0309]

Re: Mosfet Mismatch

mismatch prob, u can consider it on the aspect of offset volt

 

[forkschgrad]

Re: Mosfet Mismatch

any layout books that will not discuss it is a dump.

 

[dabing]

Re: Mosfet Mismatch

In my opinion
first, you can use symmetry structure which you can find in many books.
second, you can refer to the foundry which you can get their PCM or electronics parameter, and maybe here are some discreption about mismatch parameter. You can calculate the MOS by the mismatch parameter.
third, you could know the circuit's precision.

 

[tia_design]

Re: Mosfet Mismatch

There are two ways to reduce the offset.
1. through design. choose device with large width. output stage should be banlance to remove the systematic offset. current source's length should be maximized.


2. Through layout, using centroid and interdigitization

 

[kDaniu]

Mosfet Mismatch

tia_design, can you push me to the source where is I can read about centroid and interdigitization in layout ?


thanks, Dan

 

[layoutmaster]

Mosfet Mismatch

Read Alan Hasting's "The Art of Analog Layout", Chapter 7 is named Matching of Resistors and Capacitors but inside it mention matching techniques applicable to every component, in particular you'll find good explanations and examples of Interdigitation and CommonCentroid.

 

[chibijia]

Mosfet Mismatch

offset volt
the layut and so on all will result the mismatch!