Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Bandgap Current Reference

Status
Not open for further replies.

kishore2k4

Full Member level 5
Joined
Jun 17, 2006
Messages
296
Helped
44
Reputation
88
Reaction score
10
Trophy points
1,298
Location
Middle Earth
Activity points
3,295
current reference

Hi,

I am looking for a bandgap current reference circuit (0.5u n-well process) to use it as a current source for biasing circuits. My understanding is that if a reference source is temperature independant it can also be considered process(corners) independent as many process parameters change with temperature?

I came across this circuit Bandgap Current Reference in a google search. I am interesting in exploring other circuits as well. Basically I am looking for a current source/sink (Iref = approx 50uA-100uA) that can be used in my bias circuit for an op-amp.



Thank You,
 

PaloAlto

Full Member level 4
Joined
Oct 8, 2007
Messages
194
Helped
35
Reputation
70
Reaction score
9
Trophy points
1,298
Location
Cádiz, Spain
Activity points
2,506
current reference circuits current addition

Just one small correction:

kishore2k4 said:
My understanding is that if a reference source is temperature independant it can also be considered process(corners) independent as many process parameters change with temperature?

That is not true.

A reference (current and / or voltage) source can be made temperature independent.

A voltage reference source can be made corners independent.

A current reference source can NOT be made corners independent, unless you use an external resistor to generate the current. Otherwise, as you can see in your doc, it always depends on the resistor value, which is corner dependent.

If you cannot afford an external resistor, then you have to choose the resistor with smallest corner variation and design your circuit taking that variation into account. That would normally be between 10% and 40% approximately.
 

    kishore2k4

    Points: 2
    Helpful Answer Positive Rating

erikl

Super Moderator
Staff member
Joined
Sep 9, 2008
Messages
8,112
Helped
2,694
Reputation
5,368
Reaction score
2,293
Trophy points
1,393
Location
Germany
Activity points
44,063
current reference source

PaloAlto said:
Just one small correction:
...
A current reference source can NOT be made corners independent, unless you use an external resistor to generate the current. Otherwise, as you can see in your doc, it always depends on the resistor value, which is corner dependent. ...

Absolutely correct. Just one small addition: Even if you use an (external) temperature-"independent" resistor, there are still the fast/slow process corners (with all their combinations), and additionally the (statistical important) mismatch deviations (which are usually not considered as process corners, but are process dependent).
 
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top