Can I design a typical bandgap voltage reference with NPN?

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kkilambi

Joined: 06 Apr 2009
Posts: 2

04 Nov 2009 1:34 Can I design a typical bandgap voltage reference with NPN?

Can I use an NPN transistor for a Bandgap voltage reference.

I have used it just by inverting the circuit by connecting the NPN transitors to the power supply.

I am getting good nearly temperature independent bandgap voltage at 3.3 V.

But the voltage drops wit power supply naturally.

As I am simulating it for minimum and maximum cases of power supply it is changing proportionally with power supply. How do I deal with?

Thank you.

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saro_k_82

Joined: 17 May 2007
Posts: 266
Helped: 55
Location: India

05 Nov 2009 12:12 Re: Can I design a typical bandgap voltage reference with NP

I'm not sure that your process has the luxury of NPN but not the substrate PNPs.
Coming to the schematic, your reference is referred to the supply instead of ground.
If you use the PTAT current and generate the reference wrt ground you wont see huge supply dependence.

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dick_freebird

Joined: 04 Mar 2008
Posts: 307
Helped: 45
Location: USA

05 Nov 2009 16:07 Can I design a typical bandgap voltage reference with NPN?

When I was working in bipolar technologies, we used
nothing but NPNs for the reference elements. You pick
the best from what's in the basket you are given.