Low current OpAMP/Regulator design

[PatrickLee]

depletion mos voltage reference

Is anyone has experience on designing bandgap reference or op-amp with operating current around 1uA or below?

What are the limitations involved and what should be observe ?

 

[sunking]

opamp regulator

the noise and setting time

 

[gajen]

Startup time is the main issue. Then lot of nodes become really high impedance and gets coupled to power/ground noise. This makes BG outputs to completely die. So need to take care of couplings. Then area is bigger for low power bandgap due to large resistors required for this.

 

[PatrickLee]

With the BG structure described in Allen and Holberg, the resistor are in the range of over 5 MOhm in order to get a BG reference with lower than 1 uA current.
Is this approach feasible ?
Is there any ways to subsitute the high value resistor with smaller area ?

 

[sunking]

The best method is depletion mos voltage reference.

 

[PatrickLee]

What is meant by "delpetion mos voltage reference"?

Substitue the resistor with delpetion MOS ?

 

[Alles Gute]

with 1uA, you can bias your transistors in weak inversion to get high gm/I and low voltage offset. but the speed is low which is normally the limitation

 

[schwang1970]

low power opamp or current mirror you have to bias the mos in weak region than strong region.