OOppeerraattiioonnaall AAmmpplliiffiieerrss && LLiinneeaarr IInntteeggrraatteedd CCiirrccuuiittss:: TThheeoorryy aanndd AApppplliiccaattiioonn LLaabboorraattoorryy MMaannuuaall//33EE JJaammeess MM.. FFiioorree 2 Laboratory Manual for Operational Amplifiers & LIC Operational Amplifiers & Linear Integrated Circuits: Theory and Application Laboratory Manual by James M. Fiore Version 3.0.1, 01 March 2016 Laboratory Manual for Operational Amplifiers & LIC 3 This Laboratory Manual for Operational Amplifiers & Linear Integrated Circuits: Theory and Application is copyrighted under the terms of a Creative Commons license: This work is freely redistributable for non-commercial use, share-alike with attribution Published by James M. Fiore via dissidents For more information or feedback, contact: James Fiore, Professor Center for Science, Technology, Engineering and Mathematics Mohawk Valley Community College 1101 Sherman Drive Utica, NY 13501 [email protected] or via www.dissidents.com Cover photo “Canadian Shield” by the author 4 Laboratory Manual for Operational Amplifiers & LIC Introduction This manual is intended for use in an operational amplifiers course and is appropriate for two and four year electrical engineering technology curriculums. The manual contains sufficient exercises for a typical 15 week course using a two to three hour practicum period. The topics cover basic differential amplifiers through active filters. For equipment, each lab station should include a dual adjustable DC power supply, a dual trace oscilloscope, a function generator and a quality DMM. Some exercises also make use of a distortion analyzer and a low distortion generator (generally, THD below 0.01%), although these portions may be bypassed. For components, a selection of standard value ¼ watt carbon film resistors ranging from a few ohms to a few mega ohms is required along with an array of typical capacitor values (film types recommended below 1 µF and aluminum electrolytics above). A 100 ohm 5 watt power resistor is needed for the Linear Regulator exercise. A 10k Ω potentiometer will also be useful for the DC Offset exercise. Active devices include small signal diodes such as the 1N914 or 1N4148, the NZX5V1B and NZX3V3B zeners (or 1N751/1N5231 and 1N5226 in a pinch), small signal NPNs such as the 2N3904 or 2N2222, a medium power NPN transistor such as the 2N5192G, and a variety of inexpensive op amps such as the 741, LF351 or TL081, LF411 and LM318. Most circuits use standard +/-15 VDC power supplies. All DC supplies should be bypassed with 1 µF capacitors positioned as close to the IC and ground as possible. The DC supplies are not drawn in detail on the schematics in order to reduce visual clutter, although the bypass capacitors are included in the parts lists as a reminder. Each exercise begins with an Objective and a Theory Overview. The Equipment List follows with space provided for model and serial numbers, and measured values of components. Schematics are presented next along with the step-by-step procedure. Many exercises include sections on troubleshooting and/or design. Simulations with Multisim are often presented as well, although any quality simulation package such as PSpice, LTspice or TINA-TI can be used instead. All data tables are grouped together, typically with columns for the theoretical and experimental results, along with a column for the percent deviations between them. Finally, a group of appropriate questions are presented. Other laboratory manuals in this series include DC and AC Electrical Circuits, Semiconductor Devices (diodes, bipolar transistors and FETs), Computer Programming with Python™ and Multisim™, and Embedded Controllers Using C and Arduino. A text is also available for Embedded Controllers and the third edition of the companion Op Amps & LIC text will soon be available (mid 2016). A Semiconductor Devices text is due in 2017. All of these titles are Open Educational Resources using a Creative Commons non-commercial share-alike with attribution license. Laboratory Manual for Operational Amplifiers & LIC 5 A Note from the Author This manual was created to accompany the text Operational Amplifiers & Linear Integrated Circuits: Theory and Application. It is used at Mohawk Valley Community College in Utica, NY, for our ABET accredited AAS program in Electrical Engineering Technology. I am indebted to my students, co-workers and the MVCC family for their support and encouragement of this project. The text and this manual were published originally via the traditional route. When the opportunity arose, as a long-time supporter and contributor to the Open Educational Resource movement, I decided to re-release these titles using a Creative Commons non-commercial, share-alike license. I encourage others to make use of this manual for their own work and to build upon it. If you do add to this effort, I would appreciate a notification. “We need not stride resolutely towards catastrophe, merely because those are the marching orders.” - Noam Chomsky 6 Laboratory Manual for Operational Amplifiers & LIC Table of Contents Decibels and Bode Plots . . . . . . 8 The Differential Amplifier . . . . . . 14 The Op Amp Comparator . . . . . . 22 The Non-inverting Voltage Amplifier . . . . . 28 The Inverting Voltage Amplifier . . . . . 34 The Op Amp Differential Amplifier . . . . . 38 Parallel-Series and Series-Series Negative Feedback . . 44 Gain-Bandwidth Product . . . . . . 50 Slew Rate and Power Bandwidth . . . . . 56 The Noncompensated Op Amp . . . . . 60 DC Offset . . . . . . . . 64 The Operational Transconductance Amplfier . . . 70 Precision Rectifiers . . . . . . . 74 Function Generation . . . . . . . 80 The Linear Regulator . . . . . . . 86 The Triangle-Square Generator . . . . . 90 The Wien Bridge Oscillator . . . . . . 94 The Integrator . . . . . . . . 98 The Differentiator . . . . . . . 102 VCVS Filters . . . . . . . . 106 The Multiple Feedback Filter . . . . . . 114 The State-Variable Filter . . . . . . . 120 Appendix A: Creating Graphs Using a Spreadsheet . . 128 Appendix B: Manufacturer’s Datasheet Links . . . 130 Laboratory Manual for Operational Amplifiers & LIC 7 Decibels and Bode Plots Objective In this exercise, the usage of decibel measurements and Bode plots will be examined. The investigation will include the relationship between ordinary and decibel gain, and the decibel-amplitude and phase response of a simple lag network. Theory Overview The decibel is a logarithmic-based measurement scheme. It is based on ratios of change. Positive values indicate an increase while negative values indicate a decrease. Decibel schemes can be used for gains and, with minor modification, signal levels. A Bode plot shows the variations of gain (typically expressed in decibels) and phase across a range of frequencies for some particular circuit. These will prove to be very valuable in later design and analysis work. Reference Fiore, Op Amps and Linear Integrated Circuits Section 1.2, The Decibel Section 1.3, Bode Plots Equipment (1) Oscilloscope model:________________ srn:__________________ (1) Function generator model:________________ srn:__________________ (1) Decibel-reading voltmeter model:________________ srn:__________________ (1) DMM model:________________ srn:__________________ Components (1) 100n F actual:__________________ (1) 100  actual:__________________ (1) 1k  actual:__________________ (1) 4k7  actual:__________________ (2) 10k  actual:__________________ __________________ (1) 22k  actual:__________________ 8 Laboratory Manual for Operational Amplifiers & LIC Schematics Figure 1 Figure 2 Laboratory Manual for Operational Amplifiers & LIC 9 Procedure 1. Calculate the voltage gains (losses) for the voltage divider of Figure 1 for the resistor values specified, and record them in Table 1. Also, convert each of the ordinary gains into decibel form. 2. Assemble the circuit of Figure 1 using the 22k resistor. 3. Set the generator to a 100 Hz sine wave, 0 dBV (Note: If the meter is calibrated in dBu, then use 0 dBu). 4. Apply the generator to the circuit. Measure and record the output voltage in Table 1 using the decibel- reading voltmeter. Also, compute the resulting experimental decibel voltage gain and gain deviation. 5. Repeat step 4 for the remaining resistor values in Table 1. 6. To create a simple Bode plot, the lag network of Figure 2 will be used. Assemble this circuit and record its theoretical critical frequency in Table 2. 7. Set the generator to a 1 kHz sine wave, 0 dBV. 8. Apply the generator to the circuit. Determine the experimental critical frequency by adjusting the frequency of the generator until the circuit’s output voltage is –3 dBV. Record the measured frequency in Table 2. 9. Set the generator to a sine wave at one-tenth of the experimental critical frequency. 10. Adjust the generator’s output level to 0 dBV. 11. Apply the generator to the circuit. Measure and record the output level in decibels in Table 3. Also, measure and record the phase angle between the input and output waveforms and record it in Table 3. 12. Repeat steps 9 through 11 for the remaining frequencies listed in Table 3. 13. Using the values from Table 3, create a Bode plot for this circuit using a log scaled horizontal axis (i.e., semi-log paper). 10 Laboratory Manual for Operational Amplifiers & LIC