Linear Electronics

ET 161 Linear Electronics

I. CATALOG DESCRIPTION:

ET161 Linear Electronics C 3, P 2, CR 4

The theory and applications of modern transistors are introduced; both the bipolar junction transistor and the field effect transistor are examined. Applications include usage in small and large signal class A amplifiers, as well as in class B power amplifiers. Voltage control FET applications are studied. Problem solving techniques involving digital computers are discussed.

Prerequisites: ET153 Introduction to Electronics, ET154 Computer Programming, or IS101 Introduction to Personal Computers, or permission of instructor.
Corequisites: ET152 Circuits 2 or permission of instructor.

II. MATERIALS:

Text: Electronic Principles 7E, Malvino, McGraw Hill Publishing
Lab Manual: Experiments for Electronic Principles 7E, Malvino, McGraw Hill Publishing
Tools: Scientific calculator, electronic hand tools and breadboard

III. STUDENT LEARNING OUTCOMES:

The student will demonstrate familiarity with the operating principles and linear applications of bipolar and field effect transistors.

The student will demonstrate a working knowledge of the basic theory of device operation, how to properly bias devices, and have an understanding of common circuit applications including small and large signal audio amplifiers.

The student will use a mathematical and problem solving approach for design and analysis, based on fundamental DC and AC circuit principles and math concepts. This will include the use of computer simulations.

The student will demonstrate facility at constructing and trouble shooting transistor circuits in the laboratory with proper use of test equipment.

The student will demonstrate appropriate communication skills, particularly technical reports through the laboratory.

The student will demonstrate the ability to work as part of a technical team, particularly in the laboratory.

Link to Course Assessment Standards

Background

Success in this course requires a good working knowledge of DC circuit principles, especially KVL and KCL. Thevenin and Superposition theorems are used quite a bit, although mesh and nodal analysis are generally not used. A basic working knowledge of diodes is assumed (such as found in chapter 3 of Malvino). AC analysis generally assumes "mid-band" frequencies, and thus phase is not usually considered (i.e., no complex impedances as found in ET152 Circuits 2). Math level is mostly algebra, although some equation proofs do require differential and/or integral calculus (not required for day-to-day calculations). For lab, you'll need the standard array of goodies as used in ET151 Circuits 1 and ET153 Intro to Electronics (breadboard, DMM, small handtools, hook-up leads, etc.) Unless otherwise specified, all lab exercises require a non-formal report due no later than one week after the exercise. Late penalty is one letter grade for the first half week, two letter grades for the second half week. Reports are not accepted beyond two weeks and receive a grade of 0. Remember, plagiarism is grounds for failure.

Link to Malvino publisher's web site for more info, self quizzes, etc.

You might enjoy Britney Spears' Guide to Semiconductor Physics

Week-by-week progress and assignments

1
Quick review of diodes on day one. Introduction to BJT and CE connection. Basic device parameters alpha and beta, and other data sheet items. Simple DC BJT model. Need for biasing, simple biasing circuits (e.g., base bias).

Reading: Introduction to diodes and semiconductors (chapters 2 and 3), and then introduction to BJTs (chapter 6). You should have completed the sections on CE connection, base and collector curves, and reading data sheets by the end of the week.
Problems: Chapter 6- 3, 5, 7, 11, 15, 17, 25.
Lab: As always, we start the semester with proper lab safety procedures. Our first experiment will be Exercise 5, Diode Curves.

2
This week we begin with simple base biasing, DC load lines and examine saturation limits. We also look at LED driver circuits. Toward the end of the week we'll be looking at other forms of bias, notably voltage divider bias.

Reading: By mid-week, complete chapter 7 through section 7. By week's end, complete sections 8-1 through 8-3.
Problems: Chapter 7- 11, 15 (this one takes some thought), 21, 27, 29, 35, 37, 39, 43. Chapter 8- 1, 7, 11, 27, 31, 37 (27 is kind of fun actually, 31 definitely requires some thought- don't get discouraged)
Lab: Exercise 15, The CE Connection. Items to note: Vbe should be fairly consistent at .7 volts, for all three transistors. Also, Ic >> Ib. Ic should vary among the three devices since it is highly unlikely that you'll pull out three with identical betas. Practical hint: although the main diagram shows two separate power supplies for Vcc and Vbb, only one supply is required since they use the same potential. Also, since several current and voltage measurements are needed for each iteration, it will be fastest if you dedicate two DMMs to current measurement (leaving them permanently wired), and a third to measure the various voltages. (Use one of the Fluke meters along with your own.)

3
We continue with biasing and introduce dual-supply emitter bias and DC coupled circuits. If time permits, we may also look at collector-feedback bias and emitter-feedback bias.

Reading: Sections 8-4 through 8-6, curve-tracer handout for lab.
Problems: 13, 15, 19 (but use figure 8-23 instead of 8-24 for problem 19). Also, redesign figure 8-23 so that Ic = 5 mA. Do this two different ways: 1) by changing Re, 2) by changing Vee. Try the DC Bias Worksheet.
Lab: Exercise 18, LED Drivers. Items to note: Like last week's lab, although two supplies are shown, only one is really needed. Don't forget that the first circuit is in saturation, thus Vce is very small, perhaps .1 volts or so. Vce(sat) can be estimated from the saturation curves found on data sheets. We will look at how to do this in lab. Also, do not ignore Vled when computing Ic(sat). A reasonable value for the LEDs we use in lab is about 2.1 volts (don't use .7 volts- these are not silicon rectifying diodes!). Finally, note that circuit two, the non-saturating driver, can be unstable and might oscillate at high frequencies. This will throw off the readings on your DMM (it might, for example, indicate that Ve > Vb). Oscillation can be verified by using the 'scope. If your circuit oscillates, it can usually be cured by placing 1 uF caps from collector to ground. Make sure that you use good layout techniques.

4
We finish biasing, including PNP devices. Once PNPs are done, we'll have the first test.

Reading: Section 8-7.
Problems: 19, 21, 23, 33.
Lab: Exercise 19, Setting up a Stable Q Point. Make sure that you measure beta for each transistor, either by using the curve tracer or by directly measuring base current (and then computing beta from Ic/Ib). For the lab write-up, compare the beta spreads versus the Ic spreads. Are the circuits stable in terms of Ic versus beta?

5
We tidy up biasing (going over the test) and introduce AC models and equivalent circuits. This is where the circuits start to get interesting. Biasing is sort of like learning how to make a car engine idle. Now it's time to start driving. We'll spend the next couple of months looking at small signal and large signal (i.e., power) amplifier circuits.

Reading: Finish chapter 9 by friday and begin chapter 10. Pay attention to section 9-7 since it's a good overview for future work.
Problems: 5, 7, 13, 15, 17, 26.
Lab: Exercise 20, Biasing PNP Transistors. Note that circuits 1 and 2 are identical, the power supply has not been rotated in circuit 2. The only thing which has changed is the point we call "common". Ultimately, it's just a question of where to place the black lead of your voltmeter.

6
Our initial concern involves finding voltage gain, input impedance, and output impedance for typical voltage divider and dual supply emitter bias circuits. From here we will also look at the effects of source impedance and loads, and perhaps examine a few other biasing types for comparison.

Reading: Sections 10-1 through 10-4.
Problems: 1, 3, 5, 7, 11, and start Small Signal Worksheet.
Lab: Exercise 21, Transistor Bias. This lab looks at a few of the lesser known biasing schemes. In your report, rank the circuits of figures 21-1, 21-2, and 21-3 in terms of stability of Ic relative to Beta. To do this, make sure you measure the Beta of each device (either by measuring base current or by using the curve tracer). Your discussion should include a theoretical analysis of why the circuits are ranked the way they are.

7
We continue with small signal AC analysis, introducing multi-stage schemes and direct-coupled circuits. If time permits, we will introduce emitter followers and darlingtons (otherwise, it gets bounced to next week).

Reading: Finish chapter 10. Read sections 1, 2, and 4 of chapter 12 by week's end . Try the Monsterrific Problem.
Problems: 15, 17, 21, 23 from chapter 10, also 1, 3, 7, 9 and 15 from chapter 12 and finish problem set hand-out.
Lab: Exercise 23, The CE Amplifier. This is a very good first lab for small signal amplifiers. Make sure that you pay close attention to both the DC and AC measurements of table 23-1, noting how Superposition is effectively used for analysis. This is shown nicely using the oscilloscope in lab in conjunction with the AC/DC input coupling switch. Also, it is preferred to use a pair of probes where channel one is fixed to the signal generator and channel two is used for measurement of the signal under investigation. By triggering the 'scope from channel one, you'll always be able to see the magnitude and phase of the signal relative to the input.

8
We finish small signal work and have a test (end of this week or beginning of next). After this, we introduce large signal amplifiers. (Finally, we get to drive loudspeakers.)

Reading: Start chapter 11.
Problems: 3, 7, 11, 13, 15, 19.
Lab: Exercise 24, Other CE Amplifiers. This lab looks at three things: The effect of source resistance on gain, the effect of load resistance on gain, and the effect of emitter swamping on gain, distortion, and input impedance. This lab will be a formal write-up. The first two items are fairly straight forward, but the section on swamping offers more than you might think at first glance. First of all, since you will have measured both the base voltage and the generator voltage in circuits 24-1 and 24-2, you can calculate an experimental Zin (just use the voltage divider rule backwards, where one resistor -Rsource- is known, and the other -Zin- isn't). Since both circuits have identical DC bias equivalents, you can directly compare their Zin's. Second, it is possible to see the reduction in distortion that swamping causes by turning the signal generator up until the output of the amplifier starts to clip. Do this for both figure 24-1 and 24-2 and note the shape of the wave right before clipping occurs.

9
We begin detailed work on class A amplifiers including AC load lines, load power, device ratings, efficiency, etc.

Reading: Complete sections 1 through 3 and 7 of chapter 11.
Problems: 36, 37, 41, 43, 45, 47.
Lab: Exercise 25, CC and CB Amplifiers. The basic idea of any voltage follower is one of load matching. Although a follower doesn't have any voltage gain (ideally unity), it does have current gain, and thus, power gain. Therefore, a high impedance source can be connected to a low impedance load without undue loss.

10
We finish class A and start class B amplifiers. We pay particular attention to its advantages and disadvantages relative to class A operation.

Reading: Section 4 of chapter 11, sections 5 and 6 of chapter 12.See Class B Power Proof.
Problems: 19, 22, 23, 25, 35, 37.
Lab: Exercise 28, Class A Amplifiers. This lab looks at basic class A amplifiers and includes an examination of load power, device power, supplied power, and efficiency. It is important to note how low the efficiency is (for this circuit, well below the 25% theoretical maximum). Also, note how difficult it is to get a precise reading on the compliance due to the increase in distortion. It can be very instructive to take a little side trip here to investigate the effects of emitter degeneration (i.e., swamping). Simply replace the 1.8k emitter resistance with a 1.5k + 330 combo, bypassing only the 1.5k. Although the gain will drop considerably, the class A distortion will drop dramatically, allowing a much more accurate viewing of compliance and clipping.

11
Work on class B is wrapped up, including circuits utilizing direct coupled drivers and loads. We have a test on power amplifiers (end of this week or possibly the next).

Reading: Finish chapter 12.
Problems: 36, 38, 39, 41, power amplifier problem set hand-out.
Lab: Exercise 29, Class B Push-Pull Amplifiers. This is the class B output section most commercial amplifiers are based on. Pay particular attention to the bias stability gained by using a diode type bias. Also, note that notch distortion effects (i.e., crossover distortion) get worse as the signal is reduced (the exact opposite of what is seen with class A non-linearities).

12
We begin Field Effect transistors, first with how JFETs differ from BJTs, and then we launch into JFET biasing.

Reading: Start chapter 13.Here is a copy of the Self-Bias Curve.
Problems: 1, 3, 5, 7, 9, 11, 13, 15, 19.
Lab: Exercise 30, An Audio Amplifier. This is a very useful design, complete with a class A direct coupled driver. We will be altering this lab quite a bit, adding both microphones and loudspeakers.

13
JFET biasing is completed and AC amplifiers are introduced.

Reading: Complete up through section 7 of chapter 13.
Problems: 17, 21, 23, 25, 27, 31, 33, 35 (hint: think constant current source).
Lab: Exercise 32, JFET Bias. Unlike BJTs, FET biasing can be somewhat "trouble-some". The reason is because we don't have a nice fixed .7 volt drop to rely on in one of the loops. Instead, since FETs have a reverse biased gate-source, Vgs is rather flexible and can be anywhere from 0 down to Vgs(off) (perhaps as low as -8 volts in some popular devices). As it turns out, absolute stability of Id is not generally required. Unlike BJTs, the gain characteristic (i.e., gm) will not be perfectly stable if the current is stable. For highest gain stability, some fluctuation of Id is in fact desired.

14
We finish JFETs and start with MOSFET circuitry, paying attention to the differences between MOSFETs and JFETs.

Reading: Start chapter 14.
Problems: 1, 3, 7, 17, 19. Try the FET problem set handout
Lab: Exercise 33, JFET Amplifiers. Here we look at basic voltage amplifiers (common source topology) and source followers (common drain topology). Note how low the gains are when compared to their BJT counterparts. Of course, the FETs counter this by have much larger input impedance values. Zin can be loosely found through the voltage divider effect by placing a "sense" resistor in line with the gate terminal (try a 220k for starters).

15
We wrap up with MOSFETs and look at a few interesting FET applications. Time permitting, we have our last in-class test.

Reading: Finish chapter 14, also sections 8 and 9 of chapter 13.
Problems: 21, 23, 29.
Lab: Exercise 34, JFET Applications. This lab examines a few neat uses for FETs outside the realm of normal amplifiers. These include analog switches (very good for remote noiseless switching), voltage variable resistance (useful in making voltage controlled amplifiers and filters, and similar devices), and choppers (a basic building block in low drift amplifier circuits).

Resources

DC Bias Worksheet

Small Signal Worksheet

[Home] [MVCC Home]

1	Quick review of diodes on day one. Introduction to BJT and CE connection. Basic device parameters alpha and beta, and other data sheet items. Simple DC BJT model. Need for biasing, simple biasing circuits (e.g., base bias). Reading: Introduction to diodes and semiconductors (chapters 2 and 3), and then introduction to BJTs (chapter 6). You should have completed the sections on CE connection, base and collector curves, and reading data sheets by the end of the week. Problems: Chapter 6- 3, 5, 7, 11, 15, 17, 25. Lab: As always, we start the semester with proper lab safety procedures. Our first experiment will be Exercise 5, Diode Curves.
2	This week we begin with simple base biasing, DC load lines and examine saturation limits. We also look at LED driver circuits. Toward the end of the week we'll be looking at other forms of bias, notably voltage divider bias. Reading: By mid-week, complete chapter 7 through section 7. By week's end, complete sections 8-1 through 8-3. Problems: Chapter 7- 11, 15 (this one takes some thought), 21, 27, 29, 35, 37, 39, 43. Chapter 8- 1, 7, 11, 27, 31, 37 (27 is kind of fun actually, 31 definitely requires some thought- don't get discouraged) Lab: Exercise 15, The CE Connection. Items to note: Vbe should be fairly consistent at .7 volts, for all three transistors. Also, Ic >> Ib. Ic should vary among the three devices since it is highly unlikely that you'll pull out three with identical betas. Practical hint: although the main diagram shows two separate power supplies for Vcc and Vbb, only one supply is required since they use the same potential. Also, since several current and voltage measurements are needed for each iteration, it will be fastest if you dedicate two DMMs to current measurement (leaving them permanently wired), and a third to measure the various voltages. (Use one of the Fluke meters along with your own.)
3	We continue with biasing and introduce dual-supply emitter bias and DC coupled circuits. If time permits, we may also look at collector-feedback bias and emitter-feedback bias. Reading: Sections 8-4 through 8-6, curve-tracer handout for lab. Problems: 13, 15, 19 (but use figure 8-23 instead of 8-24 for problem 19). Also, redesign figure 8-23 so that Ic = 5 mA. Do this two different ways: 1) by changing Re, 2) by changing Vee. Try the DC Bias Worksheet. Lab: Exercise 18, LED Drivers. Items to note: Like last week's lab, although two supplies are shown, only one is really needed. Don't forget that the first circuit is in saturation, thus Vce is very small, perhaps .1 volts or so. Vce(sat) can be estimated from the saturation curves found on data sheets. We will look at how to do this in lab. Also, do not ignore Vled when computing Ic(sat). A reasonable value for the LEDs we use in lab is about 2.1 volts (don't use .7 volts- these are not silicon rectifying diodes!). Finally, note that circuit two, the non-saturating driver, can be unstable and might oscillate at high frequencies. This will throw off the readings on your DMM (it might, for example, indicate that Ve > Vb). Oscillation can be verified by using the 'scope. If your circuit oscillates, it can usually be cured by placing 1 uF caps from collector to ground. Make sure that you use good layout techniques.
4	We finish biasing, including PNP devices. Once PNPs are done, we'll have the first test. Reading: Section 8-7. Problems: 19, 21, 23, 33. Lab: Exercise 19, Setting up a Stable Q Point. Make sure that you measure beta for each transistor, either by using the curve tracer or by directly measuring base current (and then computing beta from Ic/Ib). For the lab write-up, compare the beta spreads versus the Ic spreads. Are the circuits stable in terms of Ic versus beta?
5	We tidy up biasing (going over the test) and introduce AC models and equivalent circuits. This is where the circuits start to get interesting. Biasing is sort of like learning how to make a car engine idle. Now it's time to start driving. We'll spend the next couple of months looking at small signal and large signal (i.e., power) amplifier circuits. Reading: Finish chapter 9 by friday and begin chapter 10. Pay attention to section 9-7 since it's a good overview for future work. Problems: 5, 7, 13, 15, 17, 26. Lab: Exercise 20, Biasing PNP Transistors. Note that circuits 1 and 2 are identical, the power supply has not been rotated in circuit 2. The only thing which has changed is the point we call "common". Ultimately, it's just a question of where to place the black lead of your voltmeter.
6	Our initial concern involves finding voltage gain, input impedance, and output impedance for typical voltage divider and dual supply emitter bias circuits. From here we will also look at the effects of source impedance and loads, and perhaps examine a few other biasing types for comparison. Reading: Sections 10-1 through 10-4. Problems: 1, 3, 5, 7, 11, and start Small Signal Worksheet. Lab: Exercise 21, Transistor Bias. This lab looks at a few of the lesser known biasing schemes. In your report, rank the circuits of figures 21-1, 21-2, and 21-3 in terms of stability of Ic relative to Beta. To do this, make sure you measure the Beta of each device (either by measuring base current or by using the curve tracer). Your discussion should include a theoretical analysis of why the circuits are ranked the way they are.
7	We continue with small signal AC analysis, introducing multi-stage schemes and direct-coupled circuits. If time permits, we will introduce emitter followers and darlingtons (otherwise, it gets bounced to next week). Reading: Finish chapter 10. Read sections 1, 2, and 4 of chapter 12 by week's end . Try the Monsterrific Problem. Problems: 15, 17, 21, 23 from chapter 10, also 1, 3, 7, 9 and 15 from chapter 12 and finish problem set hand-out. Lab: Exercise 23, The CE Amplifier. This is a very good first lab for small signal amplifiers. Make sure that you pay close attention to both the DC and AC measurements of table 23-1, noting how Superposition is effectively used for analysis. This is shown nicely using the oscilloscope in lab in conjunction with the AC/DC input coupling switch. Also, it is preferred to use a pair of probes where channel one is fixed to the signal generator and channel two is used for measurement of the signal under investigation. By triggering the 'scope from channel one, you'll always be able to see the magnitude and phase of the signal relative to the input.
8	We finish small signal work and have a test (end of this week or beginning of next). After this, we introduce large signal amplifiers. (Finally, we get to drive loudspeakers.) Reading: Start chapter 11. Problems: 3, 7, 11, 13, 15, 19. Lab: Exercise 24, Other CE Amplifiers. This lab looks at three things: The effect of source resistance on gain, the effect of load resistance on gain, and the effect of emitter swamping on gain, distortion, and input impedance. This lab will be a formal write-up. The first two items are fairly straight forward, but the section on swamping offers more than you might think at first glance. First of all, since you will have measured both the base voltage and the generator voltage in circuits 24-1 and 24-2, you can calculate an experimental Zin (just use the voltage divider rule backwards, where one resistor -Rsource- is known, and the other -Zin- isn't). Since both circuits have identical DC bias equivalents, you can directly compare their Zin's. Second, it is possible to see the reduction in distortion that swamping causes by turning the signal generator up until the output of the amplifier starts to clip. Do this for both figure 24-1 and 24-2 and note the shape of the wave right before clipping occurs.
9	We begin detailed work on class A amplifiers including AC load lines, load power, device ratings, efficiency, etc. Reading: Complete sections 1 through 3 and 7 of chapter 11. Problems: 36, 37, 41, 43, 45, 47. Lab: Exercise 25, CC and CB Amplifiers. The basic idea of any voltage follower is one of load matching. Although a follower doesn't have any voltage gain (ideally unity), it does have current gain, and thus, power gain. Therefore, a high impedance source can be connected to a low impedance load without undue loss.
10	We finish class A and start class B amplifiers. We pay particular attention to its advantages and disadvantages relative to class A operation. Reading: Section 4 of chapter 11, sections 5 and 6 of chapter 12.See Class B Power Proof. Problems: 19, 22, 23, 25, 35, 37. Lab: Exercise 28, Class A Amplifiers. This lab looks at basic class A amplifiers and includes an examination of load power, device power, supplied power, and efficiency. It is important to note how low the efficiency is (for this circuit, well below the 25% theoretical maximum). Also, note how difficult it is to get a precise reading on the compliance due to the increase in distortion. It can be very instructive to take a little side trip here to investigate the effects of emitter degeneration (i.e., swamping). Simply replace the 1.8k emitter resistance with a 1.5k + 330 combo, bypassing only the 1.5k. Although the gain will drop considerably, the class A distortion will drop dramatically, allowing a much more accurate viewing of compliance and clipping.
11	Work on class B is wrapped up, including circuits utilizing direct coupled drivers and loads. We have a test on power amplifiers (end of this week or possibly the next). Reading: Finish chapter 12. Problems: 36, 38, 39, 41, power amplifier problem set hand-out. Lab: Exercise 29, Class B Push-Pull Amplifiers. This is the class B output section most commercial amplifiers are based on. Pay particular attention to the bias stability gained by using a diode type bias. Also, note that notch distortion effects (i.e., crossover distortion) get worse as the signal is reduced (the exact opposite of what is seen with class A non-linearities).
12	We begin Field Effect transistors, first with how JFETs differ from BJTs, and then we launch into JFET biasing. Reading: Start chapter 13.Here is a copy of the Self-Bias Curve. Problems: 1, 3, 5, 7, 9, 11, 13, 15, 19. Lab: Exercise 30, An Audio Amplifier. This is a very useful design, complete with a class A direct coupled driver. We will be altering this lab quite a bit, adding both microphones and loudspeakers.
13	JFET biasing is completed and AC amplifiers are introduced. Reading: Complete up through section 7 of chapter 13. Problems: 17, 21, 23, 25, 27, 31, 33, 35 (hint: think constant current source). Lab: Exercise 32, JFET Bias. Unlike BJTs, FET biasing can be somewhat "trouble-some". The reason is because we don't have a nice fixed .7 volt drop to rely on in one of the loops. Instead, since FETs have a reverse biased gate-source, Vgs is rather flexible and can be anywhere from 0 down to Vgs(off) (perhaps as low as -8 volts in some popular devices). As it turns out, absolute stability of Id is not generally required. Unlike BJTs, the gain characteristic (i.e., gm) will not be perfectly stable if the current is stable. For highest gain stability, some fluctuation of Id is in fact desired.
14	We finish JFETs and start with MOSFET circuitry, paying attention to the differences between MOSFETs and JFETs. Reading: Start chapter 14. Problems: 1, 3, 7, 17, 19. Try the FET problem set handout Lab: Exercise 33, JFET Amplifiers. Here we look at basic voltage amplifiers (common source topology) and source followers (common drain topology). Note how low the gains are when compared to their BJT counterparts. Of course, the FETs counter this by have much larger input impedance values. Zin can be loosely found through the voltage divider effect by placing a "sense" resistor in line with the gate terminal (try a 220k for starters).
15	We wrap up with MOSFETs and look at a few interesting FET applications. Time permitting, we have our last in-class test. Reading: Finish chapter 14, also sections 8 and 9 of chapter 13. Problems: 21, 23, 29. Lab: Exercise 34, JFET Applications. This lab examines a few neat uses for FETs outside the realm of normal amplifiers. These include analog switches (very good for remote noiseless switching), voltage variable resistance (useful in making voltage controlled amplifiers and filters, and similar devices), and choppers (a basic building block in low drift amplifier circuits).