- #1
Faiq
- 348
- 16
I have a confusion understanding one of the basic assumption used for operational amplifiers which is Vin = 0 or difference of inputs = 0.
Take for example an ideal amplifier with inputs V+ and V-
V+ = 1
V- = 0.5 * Vout
Supply Voltage = +-9
Vin = V+ - V-
At start V+ = 1 and V- = 0, providing us a Vin of 1V. Since gain is infinite, Vout = +9.
Now V+=1 and V- = 4.5, providing us a Vin of -3.5. Since gain is infinite, Vout = -9
Now V+=1 and V- = -4.5, providing us a Vin of 5.5. Since gain is infinite, Vout = +9
Now V+=1 and V- = 4.5, providing us a Vin of -3.5. Since gain is infinite, Vout = -9
My question is in this example Vin doesn't approaches 0. So can you explain how does an operational amplifier will work in this situation to make Vin = 0?
Take for example an ideal amplifier with inputs V+ and V-
V+ = 1
V- = 0.5 * Vout
Supply Voltage = +-9
Vin = V+ - V-
At start V+ = 1 and V- = 0, providing us a Vin of 1V. Since gain is infinite, Vout = +9.
Now V+=1 and V- = 4.5, providing us a Vin of -3.5. Since gain is infinite, Vout = -9
Now V+=1 and V- = -4.5, providing us a Vin of 5.5. Since gain is infinite, Vout = +9
Now V+=1 and V- = 4.5, providing us a Vin of -3.5. Since gain is infinite, Vout = -9
My question is in this example Vin doesn't approaches 0. So can you explain how does an operational amplifier will work in this situation to make Vin = 0?