In the figure above V 10V and V 10 V and gain A 10000 As

In the figure above, +V = 10V and - V = -10 V and gain A = 10,000. Assuming ideal conditions, find the each of the following input voltages. To be correct the magnitude, the polarity and units must be accurate Voltage at - input Voltage at + input V_out -10 micro V -15 micro V _____________ -10 micro V +15 micro V _____________ +10 micro V -15 micro V _____________ +5 micro V 0 micro V _____________ 0 micro V +5 micro V _____________

Solution

For an ideal opamp

V_out = A(V₊ - V_-)

Case 1:

V₊ = -15uV ; V_ = -10uV

=> V_out = 10000*(-5uV) = -50 mV

Case 2:

V₊ = +15uV ; V_ = -10uV

=> V_out = 10000*(25uV) = 250 mV

Case 3:

V₊ = -15uV ; V_ = 10uV

=> V_out = 10000*(-25uV) = -250 mV

Case 4:

V₊ = 0V ; V_ = 5mV

=> V_out = 10000*(-5mV) = -50 V

But the voltage cannot reach 50 V as the driving voltage rage is -10V to 10V

So V_out will be cliped at -10V

Case 4:

V₊ = 5mV ; V_ = 0V

=> V_out = 10000*(5mV) = 50 V

But the voltage cannot reach 50 V as the driving voltage rage is -10V to 10V

So V_out will be cliped at 10V