Low power voltage reference with NPN transistor

[BKOSI.1]

Hi,

I'm looking for advise concerning a low power voltage reference using NPN transistor as following :

Q2 is used as diode (with negative TC)

Q3 is used as zener diode (with positive TC)

This circuit create a temperature-compensated +6V reference.

So my question is what parameters of Q3 permit to obtain +6.2V ?

With the same reference, provided by different manufacturer, we found different zener voltage.

If someone have the answer of this issue (or an equation), I take it !

By advance, thank you.

BR

[BKOSI.1]

 

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