Chapter 2: Difference between revisions
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*[[Chapter_1#Amplifier_Models | Zero output impedance]] |
*[[Chapter_1#Amplifier_Models | Zero output impedance]] |
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*Infinite bandwidth |
*Infinite bandwidth |
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**To allow for infinite gain regardless of the frequency? |
**To allow for infinite gain regardless of the frequency? Instantaneous feedback? |
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=Op Amp Nodal Analysis= |
=Op Amp Nodal Analysis= |
Revision as of 11:33, 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.