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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> Temperature Coefficients of PNP-Bip in BGR https://designers-guide.org/forum/YaBB.pl?num=1277030583 Message started by pancho_hideboo on Jun 20th, 2010, 3:43am |
Title: Temperature Coefficients of PNP-Bip in BGR Post by pancho_hideboo on Jun 20th, 2010, 3:43am In simulation of BGR(Band Gap Reference) circuit using standard CMOS process, I use following parameters as temperature effects in Substrate-PNP-Bip's Gummel-Poon model file. tlev=1, tlevc=1, tnom=25, xtb=0.00557, xti=3, eg=1.162 But actual measurement result of temperature dependency of our BGR circuit is fairly large than simulation. Of course, I include all temperature coefficients of other all devices such as MOSFET, resistor and capacitor. I also tried monte carlo analysis with mismatch variation while temperature sweep. Even if my design is poor as good BGR, simulation should show large temperature dependency in mismatch monte carlo analysis. But simulation don't show large temperature dependency at all. I think accuracy of our PNP-Bip model is very poor especially regarding temperature dependency. Here my questions are : (1) I 'm now suspecting that PNP-Bip give more tempereature effects than simulation. Is this reasonable ? (2) If so, should I change "xtb" parameter ? (3) Or should I specify more detailed temperature coefficients, such as tis1, tikf1, tikr1, tbf1, tvaf1, tbr1, etc. ? These parameters are common in any vendor's simulator. |
Title: Re: Temperature Coefficients of PNP-Bip in BGR Post by sheldon on Jun 20th, 2010, 4:38am Pancho, Have you looked at the statistics for Is? If the ratio is different than expected that can also effect the Temp Co of the Band Gap. Also, you might want to check the following. http://www.national.com/rap/Application/0,1570,24,00.html Best Regards, Sheldon |
Title: Re: Temperature Coefficients of PNP-Bip in BGR Post by pancho_hideboo on Jun 20th, 2010, 4:40am sheldon wrote on Jun 20th, 2010, 4:38am:
I also tried to increase mismatch variation parameter for "IS" of PNP-Bip than data provided by foundry since it is fairly small. I also tried to perturb "area" parameter of Bip. If I change these very largely but unreasonably, I can get large temperature dependency. sheldon wrote on Jun 20th, 2010, 4:38am:
Rather the followings are interesting for me. http://www.designers-guide.org/Forum/YaBB.pl?num=1276142600 http://www.designers-guide.org/Forum/YaBB.pl?num=1276024989 |
Title: Re: Temperature Coefficients of PNP-Bip in BGR Post by sheldon on Jun 20th, 2010, 5:08am Pancho, This paper maybe also useful http://users.ece.gatech.edu/rincon-mora/publicat/journals/mwscas02_bgerror.pdf Best Regards, Sheldon |
Title: Re: Temperature Coefficients of PNP-Bip in BGR Post by pancho_hideboo on Jun 20th, 2010, 5:14am sheldon wrote on Jun 20th, 2010, 5:08am:
See my original post http://www.designers-guide.org/Forum/YaBB.pl?num=1277030583/1#1 |
Title: Re: Temperature Coefficients of PNP-Bip in BGR Post by sheldon on Jun 20th, 2010, 5:26am BTW, This reference may also be useful for you "Voltage References: From Diodes to Precision High-Order Bandgap Circuits", Gabriel Alfonso Rincon-Mora |
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