1 / 26

Loop Analysis (3.2) Circuits with Op-Amps (3.3)

Loop Analysis (3.2) Circuits with Op-Amps (3.3). Prof. Phillips February 19, 2003. Op Amps. Op Amp is short for operational amplifier. An operational amplifier is modeled as a voltage controlled voltage source. An operational amplifier has a very high input impedance and a very high gain.

cloris
Télécharger la présentation

Loop Analysis (3.2) Circuits with Op-Amps (3.3)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Loop Analysis (3.2)Circuits with Op-Amps (3.3) Prof. Phillips February 19, 2003 lecture 9

  2. Op Amps • Op Amp is short for operational amplifier. • An operational amplifier is modeled as a voltage controlled voltage source. • An operational amplifier has a very high input impedance and a very high gain. lecture 9

  3. Use of Op Amps • Op amps can be configured in many different ways using resistors and other components. • Most configurations use feedback. lecture 9

  4. Applications of Op Amps • Amplifiers provide gains in voltage or current. • Op amps can convert current to voltage. • Op amps can provide a buffer between two circuits. • Op amps can be used to implement integrators and differentiators. • Lowpass and bandpass filters. lecture 9

  5. + - The Op Amp Symbol High Supply Non-inverting input Output Inverting input Ground Low Supply lecture 9

  6. The Op Amp Model v+ Non-inverting input + vo Rin + – Inverting input – A(v+ -v- ) v- lecture 9

  7. Typical Op Amp • The input resistance Rin is very large (practically infinite). • The voltage gain A is very large (practically infinite). lecture 9

  8. “Ideal” Op Amp • The input resistance is infinite. • The gain is infinite. • The op amp is in a negative feedback configuration. lecture 9

  9. The Basic Inverting Amplifier R2 R1 – + – + + Vin Vout – lecture 9

  10. Consequences of the Ideal • Infinite input resistance means the current into the inverting input is zero: i- = 0 • Infinite gain means the difference between v+ and v- is zero: v+ - v- = 0 lecture 9

  11. Solving the Amplifier Circuit Apply KCL at the inverting input: i1 + i2 + i-=0 R2 i2 R1 – i1 i- lecture 9

  12. KCL lecture 9

  13. Solve for vout Amplifier gain: lecture 9

  14. Recap • The ideal op-amp model leads to the following conditions: i- = 0 = i+ v+ = v- • These conditions are used, along with KCL and other analysis techniques, to solve for the output voltage in terms of the input(s). lecture 9

  15. Where is the Feedback? R2 R1 – + – + + Vin Vout – lecture 9

  16. Review • To solve an op-amp circuit, we usually apply KCL at one or both of the inputs. • We then invoke the consequences of the ideal model. • The op amp will provide whatever output voltage is necessary to make both input voltages equal. • We solve for the op-amp output voltage. lecture 9

  17. The Non-Inverting Amplifier + + – + – vin vout R2 R1 – lecture 9

  18. KCL at the Inverting Input + + – + – i- vin vout i1 i2 R2 R1 – lecture 9

  19. KCL lecture 9

  20. Solve for Vout lecture 9

  21. A Mixer Circuit R1 Rf + – R2 v1 – + – + + v2 vout – lecture 9

  22. KCL at the Inverting Input R1 Rf i1 if + – R2 v1 i2 – i- + – + + v2 vout – lecture 9

  23. KCL lecture 9

  24. KCL lecture 9

  25. Solve for Vout lecture 9

  26. Class Example lecture 9

More Related