Op Amp Output Voltage Swing SOLVED

Looked around, couldn't find anything on this topic: is there a way to limit the op amp output voltage swing to non-rail-to-rail performance?

by bettyandmaxsboy
October 19, 2012

Not ideal but the simplest way is to use an opamp model with supply pins and then give it dedicated supply voltage sources which you set to give the output swing you want.

If you need it to track the system supply voltages then use behavioural voltage controlled voltage sources (VCVS) for the opamp supply and use an expression in them to subtract the opamp swing margins from the actual supply voltages.

So if the supply rail is labelled as supply and the opamp can swing to within Y of the supply then the VCVS expression is:

V(supply)-Y

Another way is to use a behavioural opamp like this:

by signality
October 20, 2012

Signality, thank you! My bad on your first solution; I should have seen it, and it works for my purposes. Your second solution is quite educational. Both solutions were very helpful. Thanks again. PS: got to learn more about behavioral op amps.

by bettyandmaxsboy
October 20, 2012

I can recommend this site:

http://masteringelectronicsdesign.com/

and search for opamp model

:)

by signality
October 20, 2012

BTW: I should clarify:

"If you need it to track the system supply voltages then use behavioural voltage controlled voltage sources (VCVS) ..."

I should have said:

"... use behavioural or voltage controlled voltage sources (VCVS)"

For more on behavioural sources, see:

https://www.circuitlab.com/docs/circuit-elements/#behavioralsources

For VCVS etc., play with the Controlled Sources in the Editor and for more see this thread:

https://www.circuitlab.com/forums/support/topic/x27frca8/controlled-sources/

by signality
October 20, 2012

More good information. Thanks a ton.

by bettyandmaxsboy
October 20, 2012

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