ELECTRIC CIRCUITS ECSE-2010 Spring 2003 Class 10

1. ELECTRIC CIRCUITSECSE-2010Spring 2003Class 10

2. ASSIGNMENTS DUE • Today (Tuesday/Wednesday): • Will do Experiment #4 in Class (EP-4) • Activity 10-2 (There is no 10-1) • Thursday: • Experiment #2 Report is Due • Will do Computer Project #1 in Class (CP-1) • Will spend second hour reviewing for Exam I • Next Monday: • Exam I, 7-9, DCC 308 • Homework #4 Due • Experiment #3 Report Due • Activities 12-1, 12-2 (In Class)

3. OPEN SHOP HOURS • Wednesdays: • 9 – 11 am = Prof. Nagy • 12 – 2 pm = Prof. Millard • 2 - 4 pm = Prof. Jennings • Thursdays: • 9 - 10 am = Prof. Millard • JEC 4104:

4. REVIEW • Real Operational Amplifiers: • Rin ~ 10 M; (Very Large) • Rout ~ 100 ohms; (Very Small) • Gain = A ~ 105; (Very Large) • vout Can Never be Greater than VDC • Building Blocks for Electronic Circuits • Model Real Op Amp with Ideal Op Amp: • Rin = Infinite • Rout = 0 • Gain = Infinite • Good Model for Almost All Op Amp Circuits

5. EXAMPLE OF REAL OP AMP

6. REAL OP AMP MODEL

7. Fig. 10.1 The 741 op-amp circuit. Q11, Q12, and R5 generate a reference bias current, IREF, Q10, Q9, and Q8 bias the input stage, which is composed of Q1 to Q7. The second gain stage is composed f Q16 and Q17 with Q13 acting as active load. The class AB output stage is formed by Q14 and Q20 with biasing devices Q18 and Q19 and an input buffer Q23. Transistors Q15, Q21, Q24, and Q22 serve to protect the amplifier against output short circuit and are normally off.

8. IDEAL OP AMP

9. REVIEW • Ideal Op Amps: • ip = in = 0; Ideal Op Amp draws no current • vout can never be greater than Vdc • vout = + VDC if vp > vn • vout = - VDC if vp < vn • Comparator • Can Model Most Real Op Amps with Ideal Op Amp: • Actual behavior will only vary slightly

10. REVIEW • Op Amp with Negative Feedback: • Any circuit connection between vout and vn • Creates Virtual Short at input to Op Amp • ip = in = 0 AND vn = vp • Output can be finite • Output determined by other circuit elements • Find Output using Circuit Analysis • Look at Effects of Real Op Amps Later (usually using PSpice)

11. IDEAL OP AMP WITH NEGATIVE FEEDBACK

12. REAL OP AMP WITH NEGATIVE FEEDBACK

13. ISOLATION AMPLIFIER

14. NON-INVERTING VOLTAGE AMPLIFIER

15. INVERTING VOLTAGE AMPLIFIER

16. SUMMING AMPLIFIER

17. DIFFERENTIAL AMPLIFIERS

18. ACTIVITY 10-2

19. ACTIVITY 10-2

20. ACTIVITY 10-2

21. ACTIVITY 10-2

22. ACTIVITY 10-2 • Part b): vout in Circuit B

23. ACTIVITY 10-2

24. ACTIVITY 10-2 • Part c): RF = KR1; R3 = KR2

25. REAL OP AMPS • On Thursday, we will explore what happens when we use Real Op Amps rather than Ideal Op Amps • Will start Computer Project 1 where we will use the Circuit Model for an Op Amp and use finite Rin, non-zero Rout and finite Gain, A • Will Spend Second Hour Reviewing for Exam I

26. EXPERIMENT #4 • Let’s Look at 741 Op Amp Circuit: • 741 is a Very Common Op Amp; Cheap, Good • Will Build a Non-Inverting Voltage Amplifier • Gain ~ 2 • Must Provide + 5 V, - 5 V to Amplifier • Use E3631A Power Supply • Use + 25 V, Common to get + 5 V • Use - 25 V, Common to get - 5 V • Adjust Separately • Remember this! We will use it often

27. EXPERIMENT #4, PARTS 1 & 2

28. EXPERIMENT #4 • Will Use Oscilloscope: • Tremendous Instrument • Does Great and Wonderful Things • Make Sure Probe Attenuation Factor = 1 • Learn to Use the Functions • Will Use Function Generator: • Rs for FG = 50 ohms • Digital Voltage Readout on FG is Always Wrong when Output is plugged into Scope! • Digital Voltage Readout on FG assumes it is plugged into something with Req = 50 ohms • Always Measure Voltage Output of FG on Scope

29. 741 LAYOUT

30. EXPERIMENT #4

31. EXPERIMENT #4 8 7 6 5 1 2 3 4

32. EXPERIMENT #4

33. EXPERIMENT #4, PARTS 1 & 2

34. EXPERIMENT #4, PARTS 3-5

35. EXPERIMENT #4, PARTS 3,4,5

36. EXPERIMENT 4, PART 5

37. EXPERIMENT 4, PART 5

38. EXPERIMENT 4, PART 5

39. EXPERIMENT 4, PART 5

40. EXPERIMENT 4, PART 5

41. EXPERIMENT 4, PART 5