1 / 27

CIRCUITS WITH OPERATIONAL AMPLIFIERS

CIRCUITS WITH OPERATIONAL AMPLIFIERS. Why do we study them at this point???. 1. OpAmps are very useful electronic components. 2. We have already the tools to analyze practical circuits using OpAmps. 3. The linear models for OpAmps include dependent sources.

dea
Download Presentation

CIRCUITS WITH OPERATIONAL AMPLIFIERS

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. CIRCUITS WITH OPERATIONAL AMPLIFIERS Why do we study them at this point??? 1. OpAmps are very useful electronic components 2. We have already the tools to analyze practical circuits using OpAmps 3. The linear models for OpAmps include dependent sources COMMERCIAL PACKAGING OF TYPICAL OP-AMP

  2. LMC 6294 DIP OP-AMP ASSEMBLED ON PRINTED CIRCUIT BOARD DIMENSIONAL DIAGRAM LM 324 PIN OUT FOR LM324

  3. OUTPUT RESISTANCE INPUT RESISTANCE TYPICAL VALUES GAIN CIRCUIT SYMBOL FOR AN OP-AMP LINEAR MODEL

  4. LOAD OP-AMP DRIVING CIRCUIT COMMERCIAL OP-AMPS AND THEIR MODEL VALUES CIRCUIT WITH OPERATIONAL AMPLIFIER

  5. PERFORMANCE OF REAL OP-AMPS CIRCUIT AND MODEL FOR UNITY GAIN BUFFER WHY UNIT GAIN BUFFER? BUFFER GAIN

  6. THE IDEAL OP-AMP

  7. CONNECTION WITHOUT BUFFER CONNECTION WITH BUFFER THE VOLTAGE FOLLOWER OR UNITY GAIN BUFFER THE VOLTAGE FOLLOWER ACTS AS BUFFER AMPLIFIER THE VOLTAGE FOLLOWER ISOLATES ONE CIRCUIT FROM ANOTHER ESPECIALLY USEFUL IF THE SOURCE HAS VERY LITTLE POWER THE SOURCE SUPPLIES NO POWER THE SOURCE SUPPLIES POWER

  8. LEARNING EXAMPLE NEXT WE EXAMINE THE SAME CIRCUIT WITHOUT THE ASSUMPTION OF IDEAL OP-AMP

  9. b - d b - a REPLACING OP-AMPS BY THEIR LINEAR MODEL CONNECT THE EXTERNAL COMPONENTS LABEL THE NODES FOR TRACKING REDRAW CIRCUIT FOR INCREASED CLARITY DRAW THE LINEAR EQUIVALENT FOR OP-AMP

  10. INVERTING AMPLIFIER: ANALYSIS OF NON IDEAL CASE USE LINEAR ALGEBRA NODE ANALYSIS CONTROLLING VARIABLE IN TERMS OF NODE VOLTAGES

  11. NON-IDEAL CASE REPLACE OP-AMP BY LINEAR MODEL SOLVE THE RESULTING CIRCUIT WITH DEPENDENT SOURCES GAIN FOR NON-IDEAL CASE SUMMARY COMPARISON: IDEAL OP-AMP AND NON-IDEAL CASE IDEAL OP-AMP ASSUMPTIONS KCL @ INVERTING TERMINAL THE IDEAL OP-AMP ASSUMPTION PROVIDES EXCELLENT APPROXIMATION. (UNLESS FORCED OTHERWISE WE WILL ALWAYS USE IT!)

  12. IDEAL OP-AMP CONDITIONS LEARNING EXAMPLE: DIFFERENTIAL AMPLIFIER KCL @ INVERTING TERMINAL KCL @ NON INVERTING TERMINAL

  13. LEARNING EXAMPLE: USE IDEAL OP-AMP KCL@v1 KCL@v2 Solve for vo CAUTION: There could be currents flowing OUT of the OpAmps THE CIRCUIT REDUCES TO THIS Which voltages are set? What voltages are also known due to infinite gain assumption? Use now the infinite resistance assumption

  14. SET VOLTAGE “inverse voltage divider” LEARNING EXTENSION NONINVERTING AMPLIFIER - IDEAL OP-AMP INFINITE GAIN ASSUMPTION INFINITE INPUT RESISTANCE

  15. LEARNING EXTENSION

  16. ADD THE INPUT VOLTAGE SOURCE AND THE EXTERNAL RESISTORS THE OP-AMP FIND GAIN AND INPUT RESISTANCE - NON IDEAL OP-AMP DETERMINE EQUIVALENT CIRCUIT USING LINEAR MODEL FOR OP-AMP NOW RE-DRAW CIRCUIT TO ENHANCE CLARITY. THERE ARE ONLY TWO LOOPS

  17. COMPLETE EQUIVALENT FOR MESH ANALYSIS MESH 1 MESH 2 CONTROLLNG VARIABLE IN TERMS OF LOOP CURRENTS COMPLETE EQUIVALENT CIRCUIT NON-INVERTING OP-AMP. NON IDEAL OP-AMP

  18. THE SOLUTIONS MESH 1 MESH 2 CONTROLLNG VARIABLE IN TERMS OF LOOP CURRENTS GAIN INPUT RESISTANCE REPLACE AND PUT IN MATRIX FORM THE FORMAL SOLUTION MATHEMATICAL MODEL

  19. Sample Problem Set voltages? Use infinite gain assumption Use infinite input resistance assumption and apply KCL to inverting input Find the expression for Vo. Indicate where and how you are using the Ideal OpAmp assumptions

  20. MESH 1 MESH 2 CONTROLLING VARIABLE Sample Problem DRAW THE LINEAR EQUIVALENT CIRCUIT AND WRITE THE LOOP EQUATIONS 4. Place remaining components 1. Locate nodes 2. Place the nodes in linear circuit model TWO LOOPS. ONE CURRENT SOURCE. USE MESHES 3. Place linear model

  21. “INVERSE VOLTAGE DIVIDER” LEARNING EXTENSION

  22. ZERO-CROSSING DETECTOR COMPARATOR CIRCUITS Some REAL OpAmps require a “pull up resistor.”

  23. NON-INVERTING AMPLIFIER OP-AMP BASED AMMETER LEARNING BY APPLICATION

  24. DOES NOT LOAD PHONOGRAPH LEARNING BY DESIGN

  25. LEARNING EXAMPLE UNITY GAIN BUFFER COMPARATOR CIRCUITS ONLY ONE LED IS ON AT ANY GIVEN TIME

  26. MATLAB SIMULATION OF TEMPERATURE SENSOR WE SHOW THE SEQUENCE OF MATLAB INSTRUCTIONS USED TO OBTAIN THE PLOT OF THE VOLTAGE AS FUNCTION OF THE TEMPERATURE »T=[60:0.1:90]'; %define a column array of temperature values » RT=57.45*exp(-0.0227*T); %model of thermistor » RX=9.32; %computed resistance needed for voltage divider » VT=3*RX./(RX+RT); %voltage divider equation. Notice “./” to create output array » plot(T,VT, ‘mo’); %basic plotting instruction » title('OUTPUT OF TEMPERATURE SENSOR'); %proper graph labeling tools » xlabel('TEMPERATURE(DEG. FARENHEIT)') » ylabel('VOLTS') » legend('VOLTAGE V_T')

  27. EXAMPLE OF TRANSFER CURVE SHOWING SATURATION OUTPUT CANNOT EXCEED SUPPLY (10V) THIS SOURCE CREATES THE OFFSET THE TRANSFER CURVE KCL @ v_ IN LINEAR RANGE OFFSET

More Related