diode circuits problems and solutions pdf

Diode circuits problems and solutions pdf

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Solved Problems on Semiconductor Diode

Chapter 3. Diodes, Problem Solutions. 3.1 Problem Solution

Precise Diode Circuits

A Resistor-Capacitor-Diode RCD filter circuit the same as the RC circuit with a diode added parallel to the resistor , can improve the response time to fast undershoots, but the drop in the voltage level must be greater than the forward turn-on voltage of the diode, before the diode can start to pull RST low. These problems are not collected and graded. Problem 5.

Solved Problems On Rectifiers. Ripple Electrical Wikipedia. Power Electronics Note. Pdf Rectifiers Clippers And Clampers. Scope Noob Bridge Rectifier Hackaday.

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Learning to mathematically analyze circuits requires much study and practice. Typically, students practice by working through lots of sample problems and checking their answers against those provided by the textbook or the instructor.

While this is good, there is a much better way. For successful circuit-building exercises, follow these steps:. Avoid using the model op-amp, unless you want to challenge your circuit design skills.

There are more versatile op-amp models commonly available for the beginner. One way you can save time and reduce the possibility of error is to begin with a very simple circuit and incrementally add components to increase its complexity after each analysis, rather than building a whole new circuit for each practice problem. Another time-saving technique is to re-use the same components in a variety of different circuit configurations.

It has been my experience that students require much practice with circuit analysis to become proficient. To this end, instructors usually provide their students with lots of practice problems to work through, and provide answers for students to check their work against.

While this approach makes students proficient in circuit theory, it fails to fully educate them. They also need real, hands-on practice building circuits and using test equipment.

Another reason for following this method of practice is to teach students scientific method : the process of testing a hypothesis in this case, mathematical predictions by performing a real experiment. Students will also develop real troubleshooting skills as they occasionally make circuit construction errors. Discuss these issues with your students in the same Socratic manner you would normally discuss the worksheet questions, rather than simply telling them what they should and should not do.

I never cease to be amazed at how poorly students grasp instructions when presented in a typical lecture instructor monologue format! If your students will be working with real circuits, then they should learn on real circuits whenever possible.

If your goal is to educate theoretical physicists, then stick with abstract analysis, by all means! But most of us plan for our students to do something in the real world with the education we give them. In most sciences, realistic experiments are much more difficult and expensive to set up than electrical circuits.

Nuclear physics, biology, geology, and chemistry professors would just love to be able to have their students apply advanced mathematics to real experiments posing no safety hazard and costing less than a textbook. Exploit the convenience inherent to your science, and get those students of yours practicing their math on lots of real circuits!

A common type of graph used to describe the operation of an electronic component or sub-circuit is the transfer characteristic , showing the relationship between input signal and output signal. For example, the transfer characteristic for a simple resistive voltage divider circuit is a straight line:.

Once a transfer characteristic has been plotted, it may be used to predict the output signal of a circuit given any particular input signal. In this case, the transfer characteristic plot for the voltage divider circuit tells us that the circuit will output 3 volts for an input of 6 volts:.

We may use the same transfer characteristic to plot the output of the voltage divider given an AC waveform input:. While this example a voltage divider with a ratio is rather trivial, it shows how transfer characteristics may be used to predict the output signal of a network given a certain input signal condition. Where transfer characteristic graphs are more practical is in predicting the behavior of nonlinear circuits.

For example, the transfer characteristic for an ideal half-wave rectifier circuit looks like this:. Sketch the transfer characteristic for a realistic diode silicon, with 0. Transfer characteristic graphs provide an elegant method to sketch the output waveshape for any electrical network, linear or nonlinear.

The method in which points along an input waveform are reflected and transferred to equivalent points on the output waveform justifies the name of this analytical tool.

Make sure your students get the opportunity to learn how to use this tool, as it can provide great insight into distortion in electronic and electromagnetic devices. Determine the output voltage of this circuit, assuming a silicon diode 0. Now, determine the output voltage of the same circuit with a Schottky diode 0. Now, determine the output voltage of the same circuit with a light-emitting diode 1. Follow-up question: what is different within these three circuits, if not the output voltage?

By itself, these circuits are fairly useless. This is another example of the power of negative feedback, and an essential concept for understanding all precise opamp-driven diode circuits.

Determine the output voltage of this circuit for two different input voltage values: 5 volts, and -5 volts, assuming the use of ordinary silicon rectifying diodes:. Based on this data and any other input conditions you wish to test this circuit under , describe what the function of this circuit is.

Ask your students whether or not it matters what types of diodes are used silicon versus germanium versus light-emitting. This opamp circuit is called a precision rectifier. Analyze its output voltage as the input voltage smoothly increases from -5 volts to 5 volts, and explain why the circuit is worthy of its name:.

Assume that both diodes in this circuit are silicon switching diodes, with a nominal forward voltage drop of 0. The output of this circuit remains exactly at 0 volts for any negative input voltage.

Follow-up question: would it affect the output voltage if the forward voltage drop of either diode increased? Explain why or why not. Precision rectifier circuits tend to be more difficult for students to comprehend than non-rectifying inverting or non-inverting amplifier circuits. Spend time analyzing this circuit together in class with your students, asking them to determine the magnitudes of all voltages in the circuit and directions of current for given input voltage conditions.

Explain why the following opamp circuit cannot be used as a rectifier in an AC-DC power supply circuit:. The saddest part of this ordeal is that none of his students recognized anything wrong with his statement or at least did not feel comfortable in raising a question about it.

Predict how the operation of this precision rectifier circuit will be affected as a result of the following faults. Consider each fault independently i. The purpose of this question is to approach the domain of circuit troubleshooting from a perspective of knowing what the fault is, rather than only knowing what the symptoms are.

Although this is not necessarily a realistic perspective, it helps students build the foundational knowledge necessary to diagnose a faulted circuit from empirical data. Questions such as this should be followed eventually by other questions asking students to identify likely faults based on measurements.

The following circuit is sometimes referred to as a polarity separator. The V out1 output is the inverse negative of any positive input voltage, while the V out2 output is the inverse positive of any negative input voltage. This circuit is a good introduction to the full-wave precision rectifier circuit, although its operation there is a bit more difficult to understand than it is here. Determine the output voltage of this circuit for two different input voltage values: 4 volts, and -4 volts.

Determine the voltage at each and every node with respect to ground as part of your analysis:. It is much easier to analyze the behavior of this circuit with a positive input voltage than it is to analyze it with a negative input voltage! The error seems reasonable until an analysis of current is made. The answer to this question may seem too obvious to both asking. Since these meter movements are polarity-sensitive, their needles merely vibrate back and forth in a useless fashion when powered by alternating current:.

The same problem haunts other measurement devices and circuits designed to work with DC, including most modern analog-to-digital conversion circuits used in digital meters. Somehow, we must be able to rectify the measured AC quantity into DC for these measurement circuits to properly function. A seemingly obvious solution is to use a bridge rectifier made of four diodes to perform the rectification:.

The problem here is the forward voltage drop of the rectifying diodes. If we are measuring large voltages, this voltage loss may be negligible. However, if we are measuring small AC voltages, the drop may be unacceptable. Explain how a precision full-wave rectifier circuit built with an opamp may adequately address this situation. A precision opamp circuit is able to rectify the AC voltage with no voltage loss whatsoever, allowing the DC meter movement or analog-to-digital conversion circuit to function as designed.

The purpose of this question is to provide a practical context for precision rectifier circuits , where students can envision a real application. Suppose that diode D1 in this precision rectifier circuit fails open. What effect will this have on the output voltage? Hint: if it helps, draw a table of figures relating V in with V out , and base your answer on the tabulated results.

Instead of the output voltage remaining at exactly 0 volts for any positive input voltage, the output will be equal to the positive input voltage, assuming it remains unloaded as shown. Challenge question: what mathematical function does this circuit perform, with diode D1 failed open? Note that the given failure does not render the circuit useless, but transforms its function into something different!

This is an important lesson for students to understand: that component failures may not always results in complete circuit non-function. The circuit may continue to function, just differently. And, in some cases such as this, the new function may even appear to be intentional! Follow-up question: what function does this circuit perform? Can you think of any practical applications for it? Another facet of this question to ponder with your students is the simplification process, especially for those students who experience difficulty analyzing the whole circuit.

What simplification methods did your students think of when they approached this problem? What conclusions may be drawn about the general concept of problem simplification as a problem-solving technique?

Also, explain why a FET input opamp is required for the last stage of amplification. Challenge question: redraw the circuit, replacing the mechanical reset switch with a JFET for electronic reset capability.

Ask your students if they can think of any practical applications for this type of circuit. There are many! I find it interesting that in two very respectable texts on opamp circuitry, I have found the following peak follower-and-hold circuit given as a practical example:. This circuit contains two mistakes: the first is by having the reset switch go to ground, rather than -V.

This makes the reset function set the default output to 0 volts, which makes it impossible for the circuit to subsequently follow and hold any input signal below ground potential. The second mistake is not having a resistor before the reset switch.

Without a resistor in place, closing the reset switch places a momentary short-circuit on the output of the first opamp.

Solved Problems on Semiconductor Diode

Assuming an ideal diode what is the peak output voltage that results? What is the peak diode current? What is the average diode current? What is the maximum reverse voltage across the diode? At 20 C, voltage V is measured by a very high resistance meter to be 0. By what factor does the reverse leakage current of these diodes exceed I s?

This would make the output signal equal to 2. Figure 12 shows the circuits used to detect a modu-lated signal such as an AC or pulse signal. Ideally Q N and Q P are: 1. The current in the resistance RE in the lead is always constant. For the dc bias solution, replace all capacitors with open circuits. A Zener diode, when used in voltage stabilization circuits, is biased in a reverse bias region below the breakdown voltage b reverse breakdown region c forward bias region d forward bias constant current mode [GATE 1 Mark] Soln.

Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions. Convergence issues in resonant tunneling diode circuit simulation Abstract: Due to its status as the fastest switching semiconductor device and its bistable nature, the resonant tunneling diode RTD is considered to be one of the most promising devices for future-generation high-performance VLSI systems. However, popular circuit simulators, such as SPICE, can encounter direct current DC and transient convergence problems while simulating RTD-based circuits because of the negative differential resistance NDR in the device's current-voltage characteristics. In this paper, we study the nature of these convergence problems and provide several solution techniques that can be easily incorporated into SPICE-like circuit simulators. Wireless and Digital Imaging in the Millennium.


Assumed States for Analysis of Ideal - Diode Circuits. Example Circuit Solution By Assumed Diode States Problem Half-wave battery charger.


Chapter 3. Diodes, Problem Solutions. 3.1 Problem Solution

This course introduces students to the basic components of electronics: diodes, transistors, and op amps. It covers the basic operation and some common applications. This is a beautiful course. Be the end of the course you would definitely get confidence with the basics of electronics and once complicated circuits would look so easy to unravel. Thank you professors, you organized a very nice course.

Precise Diode Circuits

Both methods have been discussed in the video and using the diode approximation method, different circuit problems have been solved. Graphical Method: In graphical method, the load line is drawn on the V-I curve of the diode. The load line gives the possible values of voltage and current of the diode for the given circuit. The intersection of the V-I curve of the diode and the load line gives the operating voltage and current of the diode. Diode Approximation: In the diode approximation, the diode is replaced by the equivalent circuit. The link for the other useful videos related to diode: 1 Introduction to a diode and V-I characteristics of the diode.

Since the diode is ideal, it has zero resistance. Diodes D1 and D3 are forward biased while diodes D2 and D4 are reverse biased. Replacing diodes D1 and D3 by their equivalent circuits and making the branches containing diodes D2 and D4 open, we get the circuit shown in Fig.

Precise Diode Circuits

Solved Problems on Semiconductor Diode

Diodes shahriar mirabbasi department of electrical and computer engineering university of british columbia shahriar at eceubcca thanks to dr. We will discuss four methods of solving diode circuits: load line analysis, mathematical model, ideal diode circuit analysis, and constant voltage drop diode analysis. Solution Step 1. In this video, different methods for solving the diode circuits have been discussed. This course is not for advanced learners of electronics. Yan for sharing their notes on diodes the basis for these slides.

Analysis of networks employing Zener diodes is quite similar to that applied to the analysis off semiconductor i d t diodes di d iin previous i sections. Then, the other unknown quantities of the network will be determined. Basic zener regulator Analysis procedure Step 1 Determine the state of the zener diode by removing it from the network and calculating the voltage across the resulting open circuit. Step 2 Substitute the appropriate equivalent circuit and solve for the desired unknowns. Zener diodes are most frequently used in regulator networks or as a reference voltage.

Chapter 3. Diodes, Problem Solutions. 3.1 Problem Solution

Learning to mathematically analyze circuits requires much study and practice. Typically, students practice by working through lots of sample problems and checking their answers against those provided by the textbook or the instructor. While this is good, there is a much better way.

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