ME 6405 – Intro to Mechatronics Operational Amplifiers

1. ME 6405 – Intro to MechatronicsOperational Amplifiers A Gogia, Sandhu, Koenig production

2. Table of Content Overview Theory Basic circuits Advantages / Disadvantes Applications • Overview • Theory of an OP-AMP • Basic circuits • Advantages / Disadvantages • Applications A Gogia, Sandhu, Koenig production

3. Overview Overview Theory Basic circuits Advantages / Disadvantes Applications • Definition: A standard analog circuit component with two inputs, one output and a very high voltage gain.1 • Typically used for amplification, impedance matching and mathematical operations A Gogia, Sandhu, Koenig production

4. History of the OP AMP Overview Theory Basic circuits Advantages / Disadvantes Applications • Developed in the early 1940s • Before the invention of the transistor made of vaccum tubes • Became smaller with tranisistors • Today small, inexpensive integrated circuits A Gogia, Sandhu, Koenig production

5. Schematics of an OP AMP Overview Theory Basic circuits Advantages / Disadvantes Applications Circuit Design of an OP AMP A Gogia, Sandhu, Koenig production

6. Pin assignment of the IC Overview Theory Basic circuits Advantages / Disadvantes Applications Pin Configuration (1) Offset (Typically Not Used) (2) Inverting Input (3) Non-Inverting Input (4) Low Supply (5) Offset (Typically Not Used) (6) Output (7) High Supply (8) Not Connected A Gogia, Sandhu, Koenig production

7. Properties of an OP-AMP • Properties in reality • Finite input resistance • Small, but not zero output resistance • Finite gain / Saturation • Finite bandwidth Overview Theory Basic circuits Advantages / Disadvantes Applications Properties of the ideal OP-AMP • Rin is infinite • Rout is zero • Amplification Vout / Vin is infinite • Unlimited bandwidth • Zero output voltage at zero input difference • THE OP AMP WILL TRY TO MAKE THE VOLTAGE DIFFERENCE BETWEEN THE TWO INPUTS TO ZERO! • THE CURRENT INTO THE OP AMP IS ALWAYS ZERO A Gogia, Sandhu, Koenig production

8. Typical Values of an OP AMP Overview Theory Basic circuits Advantages / Disadvantes Applications A Gogia, Sandhu, Koenig production

9. Basic circuits Overview Theory Basic circuits Advantages / Disadvantes Applications • Comparator e.g. temperature sensor • Linear amplifier • Linear inverting amplifier • Impedance matching • Summing Amplifier • Subtractor • Integrator • Differentiator • Schmitt Trigger e.g. two stage comperator A Gogia, Sandhu, Koenig production

10. Nonlinear Usage - Comparator Overview Theory Basic circuits Advantages / Disadvantes Applications The nonlinear usage always works without feedback Example with reference voltage UN = 0 A Gogia, Sandhu, Koenig production

11. Linear Usage Overview Theory Basic circuits Advantages / Disadvantes Applications A Gogia, Sandhu, Koenig production

12. Inverting Amplifier Overview Theory Basic circuits Advantages / Disadvantes Applications • Input impedance infinite, therefore no current in the OP AMP • V+ - V- = 0 A Gogia, Sandhu, Koenig production

13. Non Inverting Amplifier Overview Theory Basic circuits Advantages / Disadvantes Applications • Input impedance infinite, therefore no current in the OP AMP • V+ = V- A Gogia, Sandhu, Koenig production

14. Summing Amplifier Overview Theory Basic circuits Advantages / Disadvantes Applications • Input impedance infinite, therefore no current in the OP AMP • V+ - V- = 0 A Gogia, Sandhu, Koenig production

15. Impedance matching Overview Theory Basic circuits Advantages / Disadvantes Applications Vin= Vout OP AMP tries to make the voltage difference between the inverting and the non inverting input to zero A Gogia, Sandhu, Koenig production

16. Subtracting Amplifier Overview Theory Basic circuits Advantages / Disadvantes Applications A Gogia, Sandhu, Koenig production

17. Integrator Overview Theory Basic circuits Advantages / Disadvantes Applications • Input impedance infinite, therefore no current in the OP AMP • V+ - V- = 0 A Gogia, Sandhu, Koenig production

18. Integrator (II) Overview Theory Basic circuits Advantages / Disadvantes Applications Integrate A Gogia, Sandhu, Koenig production

19. Differentiator Overview Theory Basic circuits Advantages / Disadvantes Applications Make the same calculation as with the integrator, just switch the resistor and the capacitor A Gogia, Sandhu, Koenig production

20. Schmitt Trigger Overview Theory Basic circuits Advantages / Disadvantes Applications Two stage level detector A Gogia, Sandhu, Koenig production

21. Advantages / Disadvantages Overview Theory Basic circuits Advantages / Disadvantes Applications • Advantages: cheap, easy to use, effective • Disadvantages: Ideal not possible, phase shift at high frequencies • Applications: A/D conversion, Filtering, any digital circuit A Gogia, Sandhu, Koenig production

22. Applications – D/A Converter Overview Theory Basic circuits Advantages / Disadvantes Applications Picture from Class Lecture D/A Conversion A Gogia, Sandhu, Koenig production

23. Low Pass Overview Theory Basic circuits Advantages / Disadvantes Applications A Gogia, Sandhu, Koenig production

24. Application - Rectifier Overview Theory Basic circuits Advantages / Disadvantes Applications The Schmitt Trigger can be used to rectify a signal in order to get a clock A Gogia, Sandhu, Koenig production

25. Sources • 1 www.siemensauto.com/glossaries/electronics_glossary.html • http://www.ele.uri.edu/Courses/ele343/low.pass/ • Pictures of example circuits taken from http://www.fh-landshut.de/~wlf/schT/Vorlesung/ST_3.pdf http://www.elektronik-kompendium.de/sites/bau/0209092.htm • Some pictures taken from Garcia-Rivera, Newby, Rogge, Presentation on the 25th of September 2003 in the ME 6405 class (www.me.gatech.edu/mechatronics_course) A Gogia, Sandhu, Koenig production

26. Questions? A Gogia, Sandhu, Koenig production

27. An output of the Gogia, Sandhu, Koenig brain factory A Gogia, Sandhu, Koenig production