How current mirrors are used to maintain fixed current while temperature changes?

[ssayan79]

Hi

i need a great help. I know that the current mirror is used to polarize amplifiers. I don't understand how current mirrors is used mantain fixed the current with the change of temperature. I need formulas.

Thenk you very much

 

[monnoliv]

Re: Current Mirror

Because on first order, calculations are not Vbe dependant (Vbe are the same, then the two Ib are the same), then no temperature dependance, see here:
https://en.wikipedia.org/wiki/Current_mirror
Regards,

 

[megzhuy]

Current Mirror

You can use Iptat plus Ictat, then you can get the constant current.

 

[supreet_95]

Current Mirror

No need to use Iptat or Ictat, in current mirrors we can maintain the same Vgs, Vds and hence the region for the both transistors. They can be kept same irrespective of power supply or temperature and hence can be kept constant. However the reference current itself will chnge with vpwr and temp.

 

[chibijia]

Current Mirror

you must work on saturation region,or you won't get what you want!

 

[Sadegh.j]

Re: Current Mirror

Well, not all of them have temperature stability, unless designed for such a feature. One thing that can be done is to make sure the two bottom transistors are close to one another