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Mohit

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USA

Basic but confusing question regarding mosis
Jul 18^th, 2004, 1:00am

Please help me with the following questions, they have confused me a lot

1) In the spice parameters file provided by mosis (for example http://www.mosis.org/cgi-bin/cgiwrap/umosis/swp/params/tsmc-035/n88y-params.txt), What does K' refers to, it says here that K' is (uo*Cox/2) but when i use this value for my simulations I dont get a correct result, rather this K' value is closer to uo*cox.

2) If I have to find Ro for a MOS transistor, i use formula 1/(lambda*Id), where lambda is channel length modulation factor, how can I find lambda using this spice file.
I dont want to find exact Ro for each transistor, but would like to know the approximate value which I should use for hand calculations and basic analysis.

Thankyou

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Frank Wiedmann

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Posts: 678
Munich, Germany

Re: Basic but confusing question regarding mosis
Reply #1 - Jul 18^th, 2004, 11:45pm

Quote:

1) In the spice parameters file provided by mosis (for example http://www.mosis.org/cgi-bin/cgiwrap/umosis/swp/params/tsmc-035/n88y-par ams.txt), What does K' refers to, it says here that K' is (uo*Cox/2) but when i use this value for my simulations I dont get a correct result, rather this K' value is closer to uo*cox.

Why don't you just ask them directly (or try the MOSIS User Group)? See http://www.mosis.org/support/customer.html.

Quote:

2) If I have to find Ro for a MOS transistor, i use formula 1/(lambda*Id), where lambda is channel length modulation factor, how can I find lambda using this spice file.
I dont want to find exact Ro for each transistor, but would like to know the approximate value which I should use for hand calculations and basic analysis.

The most simple and most accurate way to find Ro is probably to perform a dc sweep simulation and to look at the slope of the curve in the saturation region.

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forestmay New Member Offline Posts: 3	Re: Basic but confusing question regarding mosis Reply #2 - Aug 5^th, 2004, 3:39am after .dc sweep , u can use the following fomula in spice .probe ro = par('1/gdso(m)') to caculate the output resistance of the transistor m. WHO can help me to caculate the Rout of a circuit, for instance a casocde current source?
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kokabanga Junior Member Offline Posts: 28	Re: Basic but confusing question regarding mosis Reply #3 - Aug 6^th, 2004, 11:31pm same thing do a DC sweep of a dc output voltage source connected externally from o/p pin to gnd.....and then plot slope of iout wrt vout....this is possible in ide based simulators like ewb, cadence, mg..dunno in spice if u can plot slope
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