Discrete low current voltage reference

[tinska.h]

Hi everyone,

I need to make a low current voltage reference with discrete components. I'm familiar with Zener based devices and TL431, but they are drawing too much quiescent current in order to have accurate regulation. My target is to be 10µA - 50µA (quiescent).

I have studied a bit of voltage references based on P-N bandgap, by simply using BJT's Vbe or diode's Vf as reference, but they will have poor temperature performance. I know that Bandgaps can be compensated by CTAT PTAT(??) but are they suitable for discrete component implementations? Also would Vbe characteristics of BJT vary significantly from one batch to another?

Or I could tolerate a small temperature coefficient, I don't know if there are more simplified bandgap references (with poorer temp. performance) OR alternative methods than zener or bandgap which could achieve the low current performance?

Thanks in advance!

 

[dick_freebird]

Using discrete components you will lose the matching qualities
you'd like for the bandgap core. You may also find the transistors
aren't all that happy at 1uA apiece, discrete devices tend to be
larger by far than your minimum sized integrated circuit transistor.
You could buy matched transistor "ICs" but they tend to have
only a few per package of equal size, not what you need for a
well matched and production-consistent bandgap core.

You might look at outfits like Maxim, Touchstone liked to knock
off their products at lower current (but they are now belly-up).
At any rate some of the CMOS analog guys ought to have low
power reference products. And what they have, will ship trimmed
and tight.

 

[crutschow]

How about the LT1634 shunt regulator? It can operate down to 10µA