Continue to Site

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.

Register Log in

about constant gm bias

Status
Not open for further replies.
jecyhale

jecyhale

Advanced Member level 1
Joined
Feb 19, 2008
Messages
401
Helped
54
Reputation
108
Reaction score
8
Trophy points
1,298
Location
China
Activity points
3,001
Hi, all

I have designed a constant gm bias, and the gm=1/R
So, my question is how to confirm the value of R is a constant?

We know the R will change with PVT more than 20% usually.

Thanks.
 

The constant gm bias won't supply constant gm, but constant gm*R and since R is very process variant, you won't get a constant gm across process corners. You would want to use this kind of bias at applications where constant gain is required where gain=gm*R.

If you're in real need of constant gm indep on R, you may need to trim the resistors used at constant-gm circuit, but this is very expensive.
 

    jecyhale

    jecyhale

    Points: 2
    Helpful Answer Positive Rating
ieropsaltic said:
The constant gm bias won't supply constant gm, but constant gm*R and since R is very process variant, you won't get a constant gm across process corners. You would want to use this kind of bias at applications where constant gain is required where gain=gm*R.

If you're in real need of constant gm indep on R, you may need to trim the resistors used at constant-gm circuit, but this is very expensive.
Click to expand...


Thanks.

So I have used three current refference, the iPTAT, VBG/R, and constant Gm.
I think this three current reference are all process variant.
isn't it?
So
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top