CHARACTERISTICS OF IDEAL OP AMP

CHARACTERISTICS OF IDEAL OP AMP

Here we are going discuss about the Ideal OP-AMP characteristics or assumptions.

An operational amplifier is said to be IDEAL if it has the Following CHARACTERISTICS :-

1. Its open loop gain A is infinite.

1. Its open loop gain A is infinite.

When an operational amplifier (OP-AMP) is operated without any connection between the output and any of the inputs (without feedback), it is said to be in OPEN LOOP condition.

Infinite voltage gain means the voltage difference required between the two inputs to produce any output voltage is zero.

2. The Input Resistance should be Infinite.

2. The Input Resistance should be Infinite.

The Input current is zero and so it doesnot load the source. It is also means the ideal OP AMP is a voltage controlled device.

3. The output Impedence should be Zero.

3. The output Impedence should be Zero.

The output voltage Vout doesnot depend on the Load Resistance connected between the output terminals. So the output voltage is independent of current drawn by the Load. Thus the device can drive Infinite number other devices.

4. Perfect Balance

4. Perfect Balance

Because of Infinite voltage gain, the voltage between Inverting and Non-Inverting terminals of Input is essentially Zero.

5. Infinite Frequency Bandwidth

5. Infinite Frequency Bandwidth

It has flat Frequency response from dc to infinity so that any Frequency signal from Zero to infinity Hz can be amplified without attenuation.

6. Drift in Characteristics with Temperature should be Zero

6. Drift in Characteristics with Temperature should be Zero

The output must be independent of temperature variations

7. Common mode rejection ratio (CMRR) should be infinite

7. Common mode rejection ratio (CMRR) should be infinite

If the CMRR is infinite for an OP AMP, it will be free from unusual voltage pick-up, thermal noise etc.

8. Slew rate is Infinite

8. Slew rate is Infinite

So that output voltage changes simultaneously with Input.

9. Offset Voltage should be Zero

9. Offset Voltage should be Zero

The output Voltage must be Zero where Input is Zero.

**Ideal Characteristics are only for assumptions**so that analysis of Operational amplifier can be simplified.

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