The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
May 20th, 2019, 3:38am
Pages: 1
Send Topic Print
Giving an input DC bias current for an IC (Read 1407 times)
Venky_analog
Junior Member
**
Offline

Analog Design is my
trade. Math is my
love.

Posts: 10
TX, USA
Giving an input DC bias current for an IC
May 31st, 2017, 6:25pm
 
Hi,

I am trying to give the DC bias current to an IC from an external source. The way I am generating this current is by using a potentiometer structure shown below.



By changing both VDD (tunable) and R1 (potentiometer), I can change the current. The VDD comes from an LDO and hence it's kind of accurate.

The thing is I placed another series resistor R2 to reduce the variations in the current due to possible variations in the potentiometer, as I heard potentiometers are very sensitive to their environments and tend to change with time a lot.

My quesiton is if I keep R2 like 25% of R1, would it be good enough? Also, is this a good way of generating current externally for biasing circuits inside an IC?

Thanks in advance
Back to top
 
 

Either die a white noise or live long enough to see yourself become the 1/f noise.
View Profile   IP Logged
kabir_fakir
Junior Member
**
Offline



Posts: 29

Re: Giving an input DC bias current for an IC
Reply #1 - Aug 30th, 2017, 4:50am
 
For me it looks fine. I am only concerned about the thermal noise of the resistor itself as you are introducing 2 rsistors
As I did testing with my IC too. to generate the dc current, I took a clean power supply (Agilent- E3644A) and put a huge resistor (in 10k range) in series with that (instead of potentiometer ). And then I keep varying the DC power supply as per requirement of the current.
Back to top
 
 

Always a learner and will be .
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2019 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.