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temperature insenstive current source

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manissri

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from bang gap reference we get voltage which is invaraint on PVT (process supply and temperature)
but how we get the current which will be independent of supply temperature and process
 

manissri said:
from bang gap reference we get voltage which is invaraint on PVT (process supply and temperature)
but how we get the current which will be independent of supply temperature and process

Adding PTAT and CTAT currnet to get a current of independent of supply,temperature and process variation.
 

It is impossible to get a current invariant with process without external accurate resistance and trimming technic because resistor value varies much with process.
 

This is the easy part:

Copy the branch of the BGR that you produce the ΔVbe.
This will give you an almost new ctat voltage output.

Apply this to a high gain OPAMP.

Apply the output of the OPAMP to the gate of a MOSFET.

Connect the IN input to the Source of the MOSFET and via a resistor to VEE ( or gnd).

Then mirror the output current.

By trimming the resistors of the copied stage, or the current flowing there you can achieve a highly insensitive Ictat.

The one I made has a good curve around the center temperature and a typical variation of 10nA.

D.
 

leo_o2 said:
It is impossible to get a current invariant with process without external accurate resistance and trimming technic because resistor value varies much with process.

I agree. Accurate resistance cant' be realized on chip.

Added after 1 minutes:

manissri said:
from bang gap reference we get voltage which is invaraint on PVT (process supply and temperature)
but how we get the current which will be independent of supply temperature and process

But you can get insenstive current source if you can design a positive temp Voltage and use positive temp resistor at the same time.
 

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