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

When is the unity gain feedback loop unstable?

Status
Not open for further replies.
J

jackg

Newbie level 6
Joined
Jun 27, 2010
Messages
14
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Location
linkoping
Activity points
1,373
Hi all!

When is the unity gain feedback loop unstable? is it when the gain is more than 2, which might implies that the loop feeds the signal of same phase to the input making the negetive loop feedback a positive loop? I am lil confused with this more than 2 gain concept....:cry:

Thanks,
jackg
 

I'm not aware of a "more than 2 gain concept". Stability is a matter of loop phase, the gain can be very high. The loop gets exactly unstable when the oscillation condition is met (phase margin = 0), the amplifier will behave bad (overshoot, ringing) if the phase margin gets smaller than about 40 - 50 degree.

This applies to feedback amplifiers in general, not particularly for unity gain.
 

When is the unity gain feedback loop unstable? is it when the gain is more than 2

Perhaps you should reconsider your question.
A "unity gain feedback loop" with a gain "more than 2" sounds a bit contradictory, does it not?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top