Chapter 2: Difference between revisions

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*[[Chapter_1#Amplifier_Models | Zero output impedance]]
*[[Chapter_1#Amplifier_Models | Zero output impedance]]
*Infinite bandwidth
*Infinite bandwidth
**To allow for infinite gain regardless of the frequency?
**To allow for infinite gain regardless of the frequency? Instantaneous feedback?


=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.