Current reference that is independent to temperature

[anhnha]

Hi.

Could anyone suggest a current reference that generates a current about 200nA which uses only CMOS and not too big resistor and independent to temperature?
My supply voltage is a 1.8V.
I also don't want to use op amp because its size and power consumption.

 

[erikl]

See this snippet from the mentioned paper:

The residual TC depends mainly on the resistor's TC. Either use an external low TC resistor, or try to compensate with internally available resistors with known pos. and neg. TCs.

 

[anhnha]

Thanks! That circuit looks not so complicated small. However, temperature coefficient is too big. It would be great if it is small than 50ppm/C. I will try this first because at present, I have no idea to modify it to get a better TC.

 

[Dominik Przyborowski]

Maybe this one

 

[erikl]

... at present, I have no idea to modify it to get a better TC.

As I told you above: try with low TC resistor(s).

For lower TCs you need more complex circuitry, s. e.g. this figure: .
But even with that one I couldn't achieve TCs lower than a few hundred ppm/K (max. measured in industrial temperature range, not @ 25°C, of course).

For even better TC you'd perhaps want to study .

 

[anhnha]

Yeah, thank you! A lot of material to digest now! ;-)
I will try the one with the given dimensions! :lol:
BTW, I just look at the paper Dominik Przyborowski posted but I don't see Iref anywhere. That circuit looks simple but I think I am missing something.

 

[Dominik Przyborowski]

Now I'm unable to check each schematic on proposed paper, but You need to bias current source from one of diode connected transistor. Check in simulations which branches is temperature insensitive and mirror that current.