MicroElectEx1

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Ok, here's my first MicroElectrical Engineering Problem example. No differential equations here, but still much fun.

The input and output signals for an op-amp circuit are shown below. We wish to determine (a) if the op-amp circuit is linear and (b) the circuit gain.

Below: solution (a)If the circuit is linear then the output is proportional to the input. Looking at the input-output indicates that between 1.25 ms and 2.5 ms and 4 ms and 6 ms the output is constant, but the input is changing. Thus, here the op-amp circuit is in SATURATION and is NOT LINEAR!!

Below: solution (b) Between 0 and 1 ms the output is proportional to the input and it changes by 1V while the output changes by 3.3V. The gain is calculated to be V0/Vi = 3.3/1 = 3.3

In the above diagram we see the image of a unity gain circuit and its circuit model. Underneath the diagram we start KCL for the loops shown in the model.

We start with ...

Vs = IRi + IRo + AoVin

Vout = IRo + AoVin

Vin = IRi

Below we therefore see the derivation for the Unity Gain for Ro << Ri

We see that if Ao >> 1 then Vo/Vs is approximately 1.

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