Chapter 2: Difference between revisions
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=Ideal Op Amp Characteristics= |
==Ideal Op Amp Characteristics== |
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*[[Chapter_1#Amplifier_Models | Infinite input impedance]] |
*[[Chapter_1#Amplifier_Models | Infinite input impedance]] |
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*Infinite open-loop gain for the differential signal |
*Infinite open-loop gain for the differential signal |
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**To allow for infinite gain regardless of the frequency? Instantaneous feedback? |
**To allow for infinite gain regardless of the frequency? Instantaneous feedback? |
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=Op Amp Nodal Analysis= |
==Op Amp Nodal Analysis== |
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*[[Chapter_1#Amplifier_Models | No current flows into the + or - terminals]] |
*[[Chapter_1#Amplifier_Models | No current flows into the + or - terminals]] |
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*If negative feedback is present (and no positive feedback), then <math>V_+ = V_-\,</math> |
*If negative feedback is present (and no positive feedback), then <math>V_+ = V_-\,</math> |
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Revision as of 13:14, 11 January 2010
Ideal Op Amp Characteristics
- Infinite input impedance
- Infinite open-loop gain for the differential signal
- Zero gain for the common mode signal
- You can easily change an differential amplifier into a common-mode amplifier by grounding one of the inputs
- Zero output impedance
- Infinite bandwidth
- To allow for infinite gain regardless of the frequency? Instantaneous feedback?
Op Amp Nodal Analysis
- No current flows into the + or - terminals
- If negative feedback is present (and no positive feedback), then
- Write nodal equations at and , but not at
- There is a voltage source inside the op amp. Writing a nodal equation at a voltage source adds an extra equation and an extra variable. You gain no ground.
