The concept of Large signal voltage gain 's measurement condition ?

Hi

I would like to know how to decide the condition of "Large signal voltage gain".

For example, AD8542's condition is

Vs=2.7V VCM=1.35V

    RL=100Kohm Vo=0.5 to 2.2V

Vs=5V VCM=2.5V

    RL=100Kohm Vo=0.5 to 2.2V

How to decide this vo condition?

Why 0.5?   Why 2.2V?

Other case,  OP295's condition is

Vs=5V VCM=2.5V

   RL=10Kohm  0.005V<= Vout <= 4.0V

Vs=+/-15V

     RL=10Kohm    no output voltage description.

in this case why 0.005V?  Why 4.0V?

In AD8542 case, Vs=5.0V, 3.0V's vo conditions are same as Vs=2.7V.
It means to cut the test ?  and Avo does not depend on Vs voltage?

For example, condition is Vo= 0.1V to 2.5V,then how much the Avo will degrade?

In OP295's case, why vo is very low?

I would like to know the concept of vo decision.

Regards

moto

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  • 0
    •  Analog Employees 
    on Dec 16, 2013 10:10 PM

    Hi, moto.

    Avo depends on supply voltage but the AD8542 does not follow this. I don't know why. Usually, for the newer datasheets, the Vo is set to be between 0.5V to 1.5V away from the rails in order to have a better Avo value and this Vo depends on Vsy.  

    For the OP295, the Vo range was chosen because it is the range that gives a good Avo number.

    Hope this helps.

    Regards,

    Anna

Reply
  • 0
    •  Analog Employees 
    on Dec 16, 2013 10:10 PM

    Hi, moto.

    Avo depends on supply voltage but the AD8542 does not follow this. I don't know why. Usually, for the newer datasheets, the Vo is set to be between 0.5V to 1.5V away from the rails in order to have a better Avo value and this Vo depends on Vsy.  

    For the OP295, the Vo range was chosen because it is the range that gives a good Avo number.

    Hope this helps.

    Regards,

    Anna

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