analog layouts--- p+ poly resis prefered ???

in analog layouts .. we prefer p+ poly resistors over n+ poly resistors .... coz it says that we have better matching in the previous case ... could nybody explain me why is it so... ??? r we talkin about doping concentrations to be more variable in case of n+ ... or is there some other reason ??? coz when it come to putiing up an n+ over diff its better considered in terms of least variability in doping concentration, am i right . please help ..!! thanx & regards naman.

Asked By: metal
On: Jul 18, 2005 8:32:28 AM

Comments(4)

Hi, I would like to add one more point to this is, P+ poly resistors SHEET RESISTANCE and MATCHING COEFFICIENT is more when compared to N+ poly resistors. Thanks and Regards Jaggi

Comment By: jaggi
On: Oct 18, 2005 6:28:28 PM

hi anil, hey im sorry i culdnt send over that material to you as it is only as a hardcopy with me ... infact i could just be more descriptive with the line that i could read and jot for you here " p+ poly resistors match better over n+ poly resistors, so the prefernce of using a p+ poly resistor is more and should always be preffered unless required" i feel the question hs much to do with material science rather than analog, beta matching in n type and p type could be one of the factors for the same what do you say ...??

Comment By: metal
On: Aug 23, 2005 12:12:43 AM

thanx venk..... but i think i have not put accross my question clearly to you my question is why for use as a resistor ... we prefer using p+ poly resistors..... the reason i got from one of the manuals was that there is a better matching possiblity in case of p+ poly resistors compared to n+ poly resistors please clarify the reason for this matching difference ..???? thanx once again,

Comment By: metal
On: Jul 21, 2005 2:24:32 AM

metal , i hope u know the reason of N+ being used as the poly.i donno the P+ transition from the former. N+ is used because of its better conductance over P+ poly as all of us know.fabrication will be made easy if we use poly(again silicon only so easy) instead of metal.

Comment By: venkateshr
On: Jul 18, 2005 9:52:18 AM

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