Download Elektrotehniško-računalniška strokovna šola in gimnazija Ljubljana

Elektrotehniško-računalniška strokovna šola in gimnazija Ljubljana
UČNA PRIPRAVA ZA TIMSKO POUČEVANJE
Team Teaching Preparation
Predmet/-a/-i Subject(s)
Učitelja/-i
Teachers
Letnik, razred
Class
ELK3P / English
Igor Petrovčič / Amresh Prakash Torul
Učni sklop, tema
Topic
Feedback Theory and Operational Amplifier
Zaporedna št. ure
No of lessons
G3B – Block of 2 hours
G3A – Block of 2 hours [repeated]
Učilnica
Classroom
K5
G3.A / G3.B
Žarišče ure oz. sklopa (npr. razvijanje kritičnega mišljenja):
Lesson focus:
English for Specific Purpose, Content-based foreign language learning
Vrsta timskega poučevanja
Team teaching type
Alternative, Parallel
Učna oblika
Teaching design
Frontal, Working in pairs
Učna metoda
Teaching method
Explanation/Conversation
Učna sredstva in pripomočki
- za učitelja:
- za dijake
- internet, handout
- internet, handout, Moodle
Teaching aids, devices
- teacher
- student
Potrebno predznanje dijakov:
Prior required knowledge
Students should have learnt about Feedback theory and Operational Amplifier in the
Electronics class.
CILJI 1. PREDMETA
Learning objectives (ELK3P):
Students consolidate what they have learnt about Feedback theory and Operational Amplifier
in the Electronics class.
CILJI 2. PREDMETA
Learning objectives (ENG):
- Students learn the technical English vocabulary connected to Feedback theory and
Operational Amplifier.
- Students are able to explain Feedback theory and Operational Amplifier.
SKUPNI CILJ
Common aim
Students are able to explain the basic theory of Feedback and Operational Amplifier in
Slovene and English.
Načrtovanje dela (skupni dogovori) učiteljev pred izvedbo učne ure
Teachers’ planning
Both teachers had meetings with the project leaders Ms Mojca Fink and Ms Vida Vidmar, to
agree on the approach to adopt for the ESP lessons.
To prepare for this block of 2 hours, the Electronics teacher gave the Foreign Teacher a
general idea about what the students have been learning about the selected topics. Feedback
theory and Op-Amp was taught to the students during the previous week in the Electronics
class. They also had practical experiments regarding the topics. The concepts were still fresh
for the students and we thought it was a good idea to use this opportunity for ESP.
The Electronics teacher therefore selected a few technical texts and verified the content to
make sure that it is in line with what the students already learned. The Foreign Teacher used
the content of these texts to compile a comprehension text. Much of the material had to be
adapted for the students.
Once both teachers agreed on the text, the Foreign Teacher developed the exercises to be
included in the handout. The project leaders (Ms Fink and Ms Vidmar) checked and
approved the handout.
The Foreign Teacher and the teacher of Electronics met regularly at school and from home
(using Skype) to discuss the lessons.
It was also agreed to use the e-classroom (Moodle) in order to test students. The Electronics
teacher agreed to set up the Moodle e-classroom for this activity and the Foreign Teacher
would check the students’ work and grade them.
POTEK UČNE URE
Teachers' and students' activities
Čas / Time
English teacher
15 min
Warm-up
Discussion
Open the discussion in
English/Slovene about
Feedback and OpAmp. Encourage
students to participate
and not to worry about
mistakes at this stage.
This is just a warm-up
activity.
Teacher of
electronics
Introduce the topic of
the lesson and briefly
explain what will be
done during the 2
lessons.
Dijaki
Students
Listen to the teacher
while he introduces the
topic.
Facilitate the
discussion by helping
the students when
they have difficulty.
Participate in the
discussion by
answering the questions
and asking any further
questions to the
teachers.
Make sure that every
student participates in
the discussion.
Questions asked to
students:
1. What have you
learned about
Feedback and OpAmp?
2. Describe the
experiments that
you have carried
out with Feedback
and Op-Amp.
10 min
Comprehension
Text –
individual
reading
Ask students to
underline keywords
and other difficult
words from the text
while they read.
Ask them to check the
words in the Moodle
glossary that they have
compiled.
Give students
instructions to read
the text on their own
for 10 minutes.
Read the text alone.
20 min
Comprehension
Text – class
reading
Correct students’
pronunciation mistakes
while they read.
Remind them of
Give students
instructions to read
aloud. (each student
reads one paragraph).
Read paragraph from
the text (one at a time).
Underline keywords
and other difficult
words.
Check the definitions of
the words in the
Moodle glossary.
important keywords
for each paragraph.
After each paragraph,
explain the content
briefly in Slovene,
and review the
Electronics concepts
if students have
forgotten them.
Take notes from
teachers’ explanations
and comments.
Ask students to do the
exercises alone and
then check their
answers in pairs
Do the exercises and
ask for help whenever
needed. Check answers
in pairs.
----2nd lesson---15 min
Exercises
Give students
instruction to do the
exercises that follow
the comprehension
text.
Walk around to help
students with the
Electronics part.
15 min
Exercises
Check
Walk around to help
students with English
language problems.
Supplement
explanations using
appropriate
Electronics theories.
Start checking the
answers with students.
Explain any difficult
words from the
exercises.
Help students with
Slovene translations
and explanations of
English keywords to
make sure they
understand them.
15 min
Review
Lead a similar
discussion as the one
done at the start of the
block. Use the
discussion to review
the vocabulary
covered during the
lessons.
Ugotavljanje učnih dosežkov (preverjanje, ocenjevanje)
Assessment of learning outcomes
The use of two discussions (one at the start and the other at the end) will give a general idea
of how much the students have learnt about the vocabulary related to Feedback and Op-Amp.
Students’ handouts will be collected and checked by the teachers. Moodle exercises will also
be checked.
Students will also be tested about Feedback and Op-Amp vocabulary in an English test.
Evalvacija/refleksija učiteljev / Evaluation of the lesson
This block of 2 hours followed the block about Transistors. Thanks to the good experience
acquired from those 2 lessons, as teachers, we felt more confident and the students showed
very good response to the lessons in general.
Feedback and Op-Amp was a more technical topic than Transistors, and we were interested
to find out how the students would deal with it. Before we started, the students were
confident of their knowledge mainly because the topic was still fresh in their mind. But,
again, the level of understanding of technical text varied from student to student. The
Electronics teacher had to take more time to explain the text using Slovene language in order
to get some students to understand. This led to some more time used during the reading.
After the explanation of the text, students felt more comfortable with the content and some of
them had already started to do exercises. The second discussion showed that most students
were able to explain the concepts. The exercises in Moodle were completed by students, and
they liked the idea of using the e-classroom.
Viri in literatura / Sources
http://www.allaboutcircuits.com/
http://en.wikipedia.org/wiki/Negative_feedback_amplifier
Priloge / Appendices
1. Handout (Feedback theory and Operational Amplifier)
ESP - Feedback Theory
Feedback is the process in which part of the output of a system is returned to its input in order
to regulate its further output. It can influence the input signal in one of two ways:
1. An in-phase feedback signal, which amplifies the input signal. This is known as positive
feedback.
2. A feedback signal which is inverted, causing the input signal to decrease. This is known
as negative feedback.
A feedback loop is created when all or some portion of the output from an electronic device
is fed-back to the input. A device is said to be operating open loop if no output feedback is
being employed and closed loop if feedback is being used.
A negative feedback amplifier (see below figure) is an amplifier in which a fraction of the
output is combined with the input so that a negative feedback opposes the original signal. It is
a system of three elements: an amplifier with gain AOL, a negative feedback network with a
constant β < 1 and a summing circuit acting as a “subtractor” (the white circle in the figure).
Without feedback, the input voltage V'in is applied directly to the amplifier input. The
according output voltage is given by:
The voltage gain of the amplifier with feedback, the closed-loop gain, is known as Afb. It is
given by the following equation:
Note that if there are conditions where β AOL = −1, the amplifier has infinite amplification
and then becomes an oscillator, and the system is unstable.
Negative feedback improves performance and reduces sensitivity to parameter variations due
to manufacturing or environment (e.g. temperature). Because of these advantages, negative
feedback is used in this way in many amplifiers and control systems.
Operational Amplifier
An operational amplifier ("op-amp") is a high-gain DC electronic voltage amplifier with a
differential input and, usually, a single-ended output. An op-amp produces an output voltage
that is typically hundreds of thousands times larger than the voltage difference between its
input terminals. The circuit diagram symbol for an op-amp is shown below.
= non-inverting input
= inverting input
= output
= positive power supply
= negative power supply
The amplifier's differential inputs consist of a
input and a
input, and ideally the opamp amplifies only the difference in voltage between the two, which is called the differential
input voltage. The output
voltage of the op-amp is given
by the equation,
is the voltage at the non-inverting terminal,
is the voltage at the inverting terminal and
AOL is the open-loop gain of the amplifier. The term "open-loop" refers to the absence of a
feedback loop from the output to the input.
Typically the op-amp's very large gain is controlled by negative feedback, which largely
determines the magnitude of its output ("closed-loop") voltage gain in amplifier applications.
Without negative feedback, an op-amp acts as a comparator. High input impedance at the
input terminals and low output impedance at the output terminal(s) are important typical
characteristics.
Operational amplifiers are important building blocks for a wide range of electronic circuits.
Their popularity in circuit design largely stems from the fact that characteristics of the final
elements (such as their gain) are set by external components with little dependence on
temperature changes and manufacturing variations in the op-amp itself. For this reason, Opamps are among the most widely used electronic devices today, being used in a vast array of
consumer, industrial, and scientific devices.
http://www.allaboutcircuits.com/
http://en.wikipedia.org/wiki/Negative_feedback_amplifier
Exercise 1 (True or False)
1.
2.
3.
4.
A negative feedback will cause the input signal to decrease. ______
A device using feedback is said to be operating open-loop. ______
The closed-loop gain is known as Afb. _________
If an amplifier has infinite amplification, it then becomes an oscillator. ______
5. Negative feedback increases performance and sensitivity to parameter variations due to
manufacturing or environment. ______
6. Op-amp stands for operational amplitude. ______
7. Ideally, an op-amp will amplify only the difference in voltage between its two input
terminals. ______
8. V+ is the voltage at the non-inverting terminal of an op-amp. ______
Exercise 2 (Matching)
closed-loop
comparator
non-inverting
input
in-phase
open-loop
inverting input
gain
inverted
feedback
1. When no feedback is being used, a device is operating _________________.
2. When feedback is being used, a device is operating _________________.
3. Waves that have the same frequency and oscillate at the same are said to be
______________.
4. An ____________________ signal clashes with another signal to cancel each other out.
5. In an op-amp, the input that is marked with a minus sign is the ___________________.
6. In an op-amp, the input that is marked with a plus sign is the ___________________.
7. A _________________ is a device that compares two voltages or currents and switches
its output to indicate which is larger.
8. _______________ is a measure of the ability of a circuit (often an amplifier) to increase
the amplitude of a signal from the input to the output.
Exercise 3 (Short answers)
1. How can feedback influence an input signal?
2. What are the elements of a negative feedback amplifier?
3. Write down the formula to calculate the output voltage of a negative feedback amplifier
operating open loop.
4. What are the advantages of negative feedback?
5. What is an operational amplifier?
6. What is the differential voltage of an op-amp?
7. In what way would an op-amp operate without negative feedback?