1 / 23

CHAPTER 8

CHAPTER 8. IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS. Op-amp circuit symbol. Open loop mode V o = A od ( v 2 – v 1 ) A od is referred to as the open loop gain. Notice that is v 2 = v 1 , the open loop gain equals to . inverting. output. non-inverting.

jeffreyperez
Download Presentation

CHAPTER 8

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. CHAPTER 8 IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS

  2. Op-amp circuit symbol • Open loop mode • Vo = Aod ( v2 – v1) • Aod is referred to as the open loop gain. • Notice that is v2 = v1, the open loop gain equals to  inverting output non-inverting

  3. Final Exam SEM II 2012/2013 An ideal op-amp, was measured in a lab experiment in open-loop mode. Determine the open loop gain (Aod) and complete the table below which shows the results of the experiment. -0.506 V 0.99 V

  4. Op amp can be configured to be used for different type of circuit applications: • Inverting Amplifier • Non – inverting Amplifier • Summing Amplifier • Integrator • Differentiator

  5. Two main characteristics: • We want the open loop gain to be equal to  which means that v2 = v1 • We also want the input resistance to be equal to  , hence there is no current going into the op-amp 0 0

  6. Inverting Amplifier Op-amp as an inverting amplifier Voltage at node 1 (inverting) = voltage at node 2 (non-inverting ) KCL at node 1: (Vi – 0) / R1 = (0– Vo) / R2 Vi / R1 = - Vo / R2 Vo = - R2 Vi R1

  7. Exercise 8.3 Gain = - (R2 / R1) = -(150/12) = -12.5

  8. Can the voltage gain be calculated using the same formula? Try and use the same method in deriving Vo/Vi

  9. Non - Inverting Amplifier Voltage at node 1 (inverting) = voltage at node 2 (non-inverting ) KCL at node 1: (0– Vi) / R1 = (Vi – Vo) / R2 -(Vi / R1) = (Vi / R2) – (Vo / R2) Vo / R2 = (Vi / R2) + (Vi / R1) = Vi 1 + 1 Vo / Vi = R2 1 + 1 R2 R1 Noninverting amplifier R2 R1

  10. Voltage Follower / Buffer Amplifier Vo = Vi Hence, gain = 1

  11. Summing Amplifier Similarly, i1 + i2 + i3 – i4 – 0 = 0 Example 8.2 Design a summing amplifier as shown in figure to produce a specific output signal, such that vo = 1.25 – 2.5 cos t volt. Assume the input signals are vI1 = -1.0 V, vI2 = 0.5 cos t volt. Assume the feedback resistance RF = 10 k

  12. Solution: output voltage

  13. Other Op-Amp Applications

  14. Integrator Integrator circuit

  15. Differentiator EXAMPLE 8.4 Differentiator circuit

  16. Calculating Gain and Design Questions NON - INVERTING INVERTING Calculating Output and Design Questions SUMMING AMPLIFIER INTEGRATOR AMPLIFIER DIFFERENTIATOR AMPLIFIER

  17. Calculate the input voltage if the final output, VO is 10.08 V. 

  18. What is the value of Vin1 from the figure above?

  19. Calculate the output voltage, VO if V1 = V2 = 700 mV

  20. IDQ

  21. Answering the questions • There are 5 questions. Answer all. • Chapter 1 & 2 will not be in the final exam • Organize your thoughts. When it is organized, so will your workflow. • Messy work will make the lecturers feel annoyed as they have to look for your answers– bear in mind that lecturer handling one section = 50-60 students – each paper has 5 questions • TOTAL – 250 to 300 questions to mark • Don’t leave a question blank – just write down anything you know that might be related • Study smart, pray and tawakal.

More Related