bias current generator (low voltage, low tempco) - question

[cmos_ajay]

Hello,
I need a bias current generator whose ouput current (ZTAT) is typically 200nA.
The desired temperature co-efficient is 250 ppm/degree Celcius
Supply voltage VDD = 1.3 volt
Temperature: -40 to +125 degree celcius
Any ideas or schematic for this bias current generator ??
Regards.

 

[Teddy]

Well I would recommend google - there is tons of stuff about this, Like the one attached. What I did not like is Idd. So I made my own @ 3uA which works @1.2V but can not share. Sorry.

 

[leo_o2]

A simple way:
a deplete NMOS + a enhanced NMOS.

 

[cmos_ajay]

Hello, I will also recommend reading 'A CMOS subbandgap reference circuit with 1-v power supply voltage' by J. Doyle .....
I used the bandgap voltage and gave it to a V-to-I converter to obtain a i(ztat)
I tried the recommended circuit , but the i(ztat) was 900 ppm/degreeC and I needed only 250 ppm/degreeC

 

[threekingtiger]

If necessary, some curvature compensation can be introduced for you BG circuit.

 

[leo_o2]

Many Japanese IC companies use this structure to design voltage reference and achieve +/-100ppm TC for LDO products.

A simple way:
a deplete NMOS + a enhanced NMOS.