Operational Amplifiers
Wednesday, 10 July 2019
6:30 PM
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Equivalent Circuit |
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Ideally, an amplifier has an infinite gain 
But, realistically, they are limited, usually (80 - 120dB)
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Ideal |
Real |
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is large |
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dB |
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Input Bias Current = |
Input Bias Current < |
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Input Offset Current = |
Input Offset Current < |
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Input Offset Voltage = |
Input Offset Voltage < |
Amplifiers amplify the difference between the inverting and non-inverting inputs.
Common Mode Rejection Ratio
The CMMR is a measure of the ability of an amplifier to amplify the difference
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differential gain
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common voltage
Golden Rules of Operational Amps
- Virtual Ground -
inverting and non-inverting inputs are at the same potential
- No current flows
into either the inverting nor non-inverting inputs
