darksteez
Newbie level 5
![Newbie level 5](/styles/images/ranks/blevel2.gif)
I've been trying to design a brokaw bandgap reference using 65nm technology, like I read the paper on this and they presented a simple schematic like this
and like i copied this circuit into my schematic and some did some hand calculations to calculate the ratio of R2/R1 with n=8. I found out that R2/R1= 5.87kOhm(approx). However, when I took R1 =1k and R2 =5.87k, the BGR output was still of CTAT nature so I kept increasing the PTAT contribution by increasing R2 to 27k-28kohms. How does this make sense? this much deviation from hand calculation?
And secondly, like I've not provided any amplification to the amplifier by adding another set of resistors to the output of the amplifier like this
so shouldn't the BGR out be near 1.2V while doing DC sweep across temperature? but my simulation shows that its already on around 2.37V. Why is it so? Please help me out with this atleast. This has been eating my head for weeks.
I'm attaching my schematic and output down below:
and like i copied this circuit into my schematic and some did some hand calculations to calculate the ratio of R2/R1 with n=8. I found out that R2/R1= 5.87kOhm(approx). However, when I took R1 =1k and R2 =5.87k, the BGR output was still of CTAT nature so I kept increasing the PTAT contribution by increasing R2 to 27k-28kohms. How does this make sense? this much deviation from hand calculation?
And secondly, like I've not provided any amplification to the amplifier by adding another set of resistors to the output of the amplifier like this
so shouldn't the BGR out be near 1.2V while doing DC sweep across temperature? but my simulation shows that its already on around 2.37V. Why is it so? Please help me out with this atleast. This has been eating my head for weeks.
I'm attaching my schematic and output down below: