Selection of diode ratio in bandgap reference voltage?

Status
Not open for further replies.
B

bharatsmile2007

Full Member level 3
Joined
Sep 19, 2007
Messages
179
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Activity points
2,306
Hello everybody,
I am new to design of BGR,
The question is that the selection of diode ration(1:n).
Commonly every one prefer 1:8 to achieve good common centroid configuration in layout. But is there any ratio which is leass than 8?

Thanks inadvance.
bharat
 

I've gone as low ad 4:1. But the higher the ratio, the stronger
your "temperature signal" will be, allowing you to use less
resistor (which is often the real driver of layout area).
 

8:1=a give nice looking layout and above 8:1 the differential voltage

Vt*ln(a)

does not increase any more significant to lower impacts from control amplifier mismatches. So it seems to be golden ratio.

A good question is what is the limit to increase the ratio "a" if there is no layout limitation.

I expect that the Vbe~log(Ic) conformance have some limits to higher current densities by parasitic resistances and to lower current densities by leakage currents. For lateral PNPs or substrate PNP's I expect at least a useable current density ratio of 1e4. So that lead to high areas.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…