Electronics - Operational Amplifiers - Discussion

Input offset voltage is the equivalent voltage at the input of an operational amplifier. If an amplifier has a voltage gain of ten and an input offset voltage of 10 microvolts, a level of 100 microvolts will appear at the output with no input. Manufacturers try to design an op amp so the input offset voltage is as small as possible to minimize this error voltage at the output of the amplifier, especially for applications where small voltages are being amplified.

Amplifier is an electronic device that increases the power of a signal. This occur due to the conversion of energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. When this is done, then an amplifier can be described as modulator of the output signal of the power supply.

By its very nature a DC circuit will not exhibit any form of Reactance, therefore, opposition to current flow will always be measured in Resistance.

Reactance exists in two forms, Capacitive & Inductive. Impedance can, therefore, be thought of as the opposition of electrical current flow in an AC circuit.

Op_amp has large input impedance to avoid loading effect. If Op_amp has very low input impedance, it would draw significant amount of current into it. It would act as large load on the circuit.

The fact that op_amp high i/p impedance ensure that it consume very little or no current from circuit.

Characteristics of an ideal operational amplifier are:
1.Infinite Open Loop Gain
2.Infinite Input Impedance
3.Zero Output Impedance
4.Infinite Bandwidth
5.Zero Output Offset
6.Zero Noise Contribution

Amplifier is electronics devices save output energy and give (save energy) to input energy with higher amplitude it's mean transmission energy between output energy and input (power supply).

Hi Meda and Komal,

I have a doubt. The Gain of OPAMP is infinite. And we know that GBW product is always constant. Then how it is possible for OPAMP to have infinite bandwidth too?

Comparator is a device to compare two signals. A and B are two signals it compare three conditions.

i.e A>B, A<B, A = B. Depending on the values it gives output.

Ideal oprational amplifier has

- open loop Gain infinte
- input impedance infinite
- output impedence Zero
- bandwidth infinite
- offset voltave zero

Negative feedback is used to stabilize voltage gain, decrease o/p impedance, increase i/p impedance, decrease distortion, increase bandwidth.