Assignment
Guangdong Institute of Education
BTECCenter
Program: Electrical/Electronic Engineering (Electronic)
Unit Title: Electronics
Unit No: 12 Assignment Title: Analyse and improve the wireless receiver(1)
Assignment No.: 1201
Issue Date: 3.06
Submission Deadline: 5.22
Assessor/Tutor: Qia-Wu Lin
Internal Verifier: Ricky Zhang
Student:
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NOTES TO STUDENTS
Check carefully the submission date and the instructions given with the assignment. Late assignments will not be accepted.
Ensure that you give yourself enough time to complete the assignment by the due date.
Do not leave things such as printing to the last minute – excuses of this nature will not be accepted for failure to hand-in the work on time.
You must take responsibility for managing your own time effectively.
If you are unable to hand in your assignment on time and have valid reasons such as illness, you may apply (in writing) for an extension.
When you refer to the work of other authors in your assignment, you must practice citation by following Harvard System for Referencing.
If you are caught plagiarizing, you could have your grade reduced to zero, or at worst, you could be excluded from the course.
STUDENT’S DECLARATION:
I confirm that this is all my own work.
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ASSESSMENT
Outcome/Grade / Criteria/
Descriptors / Evidence /
Feedback
/Assess
/ IVPass Assessment
Investigate types of amplifier / 2.1analyse the operation of different types of amplifier / ※analyse correctly the power amplifier’s voltage wave
※draw correctly the small-signal amplifier’sload line in output characteristics
2.2evaluate the actual performance of different types of amplifier / ※evaluate correctly the parameters of amplifiers
※the measure to decrease wave distortion is feasible
2.3 compare the analysis with the measured results / ※compare and analyse the experimental data
※the steps of experimental measurement areclear
※the experimental means arereasonable
2.4 modify circuit designs to meet revised specifications / ※modify the given circuit to meet the costomer’s request
※ the modified circuit is feasible
Investigate circuits with feedback / 3.1 deduce an expression for the closed loop gain of a system with feedback / ※deduce correctly the closed loop gain’ expression
※the block diagram is accurate
3.2 describe types of feedback and determine the effects on circuit performance when feedback is applied / ※describe correctly the types of feedback circuits
※analysis of the feedback effects is correct
3.3 design a circuit employing negative feedback / ※design correctly a feedback circuit to meet the customer’s request
3.4 investigate the effects of applying feedback to single and multi-stage circuits / ※investigate three working conditions of the two-stage feedback circuit
※ the calculation data is correct
Grading Assessment
M1identify and apply strategies to find appropriate solutions
/ An effective approach to study and research has been applied. / ※the strategies to modify the circuit of figure 1.1 is definite and reasonable※the strategies to design the feedback circuit is definite and reasonable
M2 select/design and apply appropriate methods/techniques / Relevant theories and techniques have been applied. / ※select a good method to draw the load line
※apply the simulation software to analyse the circuit
※grasp the experimental means to solve the circuit problem
M3
present and communicate appropriate findings / A range of methods of presentation have been used and technical language has been accurately used. / ※present and express these tasks in a fluent language
※format of this assignment is correct
※make less grammar error
D1
use critical reflection to evaluate own work and justify valid conclusion / Conclusions have been arrived at through synthesis of ideas and have been justified. / ※conclusions have been made arrived at through synthesis of ideas and have been justified
※the validity of results has been evaluated using defined criteria
D2
take responsibility for managing and organizing activities / Autonomy/independence has been demonstrated. / ※the modification of the circuit in figure 1.1 is completed independently
※the feedback circuit is designed independently
D3 demonstrate convergent/lateral/ creative thinking / Innovation and creative thought have been applied. / ※innovation and creative thought have been applied in modification the circuit in figure 1.1
※receptiveness to new ideas is evident when design the feedback circuit
※innovation and creative thought have been applied when analyse the effects of negative feedback.
Assessor’s additional comments
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Student’s Feedback
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Notes:
Assignment Description
Scenario:
Electronic circuits have already been deep into every corner of our lives. The update of electronic products is very fast. Sometimes, we need to repair electronic products so as to extend their life. Sometimes, we need to improve electronic products to meet certain specific requirements.Therefore, it is necessary for an electronic engineer to grasp the knowledge of electronic circuits.
Now, you are a product development engineer of an electronics company. The company received a business, which is to improve the wireless receiver customer provided to reach the customer’s technical requirements. As a development engineer, your task is to analyze the wireless receiver circuits, then, improve the circuits to meet customer requirements at the lostest cost.You should provide ananalysis report as detail on the following problems.
Tasks:
- (Pass Criterion 2.1) Analyse the operation of different types of amplifier.In the wireless receivercustomer provided, the audio-frequency input stage amplifier and the audio-frequency power amplifier are given below.
（Ⅰ）The audio-frequency input stage amplifier is show in figure 1.1.The relationships between collector current and collector voltage, with fixed values of base current, are given in table 1.1.You shouldmake IEQ=4mA through adjusting R5, and take this point as its quiescent operating point, then measure the value of R5 and VCEQ.
(ⅰ)Draw the static output characteristics of the transistor, use these to determine the d.c.current gain and the a.c. current gain at the quiescent operating point.
(ⅱ)The resistance value of the load is vague with age.You shouldchoose a certain value between 1.2KΩto 3KΩ anddraw the d.c. load line and a.c. load line at the static output characteristics.
(ⅲ)According to the a.c. load line, determine the maximumundistortion voltage value of the a.c. output signal.
Fig. 1.1
Table 1.1
IC(mA)VCE(V) / IB=20(μA) / IB=40(μA) / IB=60(μA)
2 / 0.8 / 2.85 / 4.6
4 / 0.9 / 3 / 4.9
6 / 1.0 / 3.1 / 5.1
8 / 1.1 / 3.2 / 5.3
10 / 1.3 / 3.3 / 5.5
（Ⅱ）The audio-frequency power amplifier is show in figure 1.2.T2, T3,C2, R3 and R4 comprise the complementary symmetry Class B circuit and T1, C1, R1, R2 comprise the pre-amplifier of the Class B power amplifier. You have to solve the following question with the electronic simulation software Multisim 10.2.
(ⅰ)List the function of each component shown in figure 1.2.
(ⅱ)Design the value of all resistors correctly so that the T3’s emitterr potential is close to half of the supply voltage, then observe the crossover distortion through adjusting R4 and draw the wave of Ui and Uo.
(ⅲ) How to reduce the crossover distortion when it occurs?List your scheme as detail and prove its effectivity.
Fig. 1.2
- (Pass Criterion 2.2) Evaluate the actual performance of different types of amplifier.
（Ⅰ）In the figure 1.1, if the current gain is in the range of 30-120, the resistance value of load RL is in the range of 1.2 to 3 . Firstly, you shouldchoose a specific value of and load, then calculate these Performance parameters at the quiescent operating pointIEQ=4mA:
(ⅰ)Voltage gain of this amplifier;
(ⅱ)Input impedance of this amplifier;
(ⅲ) Output impedance of this amplifier;
(ⅳ)If the amplitude of the input signal is further increased, the output signal will cause distortion, how to reduce this kind of distortion?List specific measures as detail.
（Ⅱ）In the figure 1.2, the range of the Vcc, RL, Vces is given in table 1.2. You shouldchoose a determined value of Vcc, RL, Vces in the table and calculate these performance parameters:
(ⅰ)The maximum of the output voltage;
(ⅱ)The maximum of the a.c. output power;
(ⅲ)The maximum of the collector efficiency .
Table 1.2
Parameter / Vcc(V) / RL() / Vces(V)Range / 12-18 / 8-16 / 1-2
- (Pass Criterion 2.3) Compare the analysis with the measured results. In figure 1.1, you should dosome experiments for this circuit in the lab, keep the measured results with pictures or tables.
（Ⅰ）Debug the quiescent operating point throughadjusting the resistor R5;
（Ⅱ）Measure the voltage gain at the quiescent operating pointIEQ=4mA;
（Ⅲ）Measure the maximum non-distortion output voltage;
（Ⅳ）Adjust the circuit parameters and observe the cut-off distortion waveform and saturation distortion waveform. Record the experiment process;
（Ⅴ）Calculate the voltage gain and current gain with the electronic simulation software Multisim.
（Ⅵ）Analyse the difference between experimental data and simulation data.
4. (Pass Criterion 2.4) Modify circuit designs to meet revised specifications. To the circuit of figure 1.1, the customer's request is that when the load resistance decreases by 50%, the circuit's voltage gain can remain little chang.As a product development engineer, you should give ascheme to meet the customer’s request and prove the feasibility of your scheme.
5. (Pass Criterion 3.3, 3.1)Design a circuit employing negative feedback. Deduce an expression for the closed loop gain of a system with feedback.Customer required to add a amplifier circuit in the audio amplification part of the wireless receiver. The technical requirements of the designed amplifier are:
(a) The input impedanceis big enough to meet the voltage source which has a internal resistor with a certain resistance;
(b) Output voltage should be stable;
(c) Adopt certain measures to stabilize the quiescent operating point;
(d) The voltage gain is big enough,.
You should do:
（Ⅰ）Design the amplifier.
（Ⅱ）Deduce an expression for the closed loop gain of this amplifier.
6. (Pass Criterion 3.2, 3.4) Describe types of feedback and determine the effects on circuit performance when feedback is applied.Investigate the effects of applying feedback to single and multi-stage circuits. The circuit in figure 1.3 is an audio frequency multi-amplifier in the wireless circuit and the value of R8 is vague with age.The customer tell you the value of R8 is in the range of 1.2 to 3 .There are three states in the circuit.
(a)There is no feedback in the second stage circuit when switch J1 is on and J2 is off.
(b)There is a feedback loop in the second stage when switch J1 is off and J2 is off. (c)There is a feedback loop betweentwo stages when switch J1 is on and J2 is on.
With the experimental measurement data or the simulation results or the principle calculating, you have to do:
（Ⅰ）Describe types of feedback in the circuit and determine the effects on circuit performance when feedback is applied.
（Ⅱ）Calculate the input impedance, output impedance, voltage gain, frequency response when the circuit is in state (a).
（Ⅲ）Calculate the input impedance, output impedance, voltage gain, frequency response when the circuit is in state (b).
（Ⅳ）Calculate the input impedance, output impedance, voltage gain, frequency response when the circuit is in state (c).
（Ⅴ）Analyse the above data and make your conclusion about the effects of applying feedback to single and multi-stage circuits.
Fig. 1.3
Reference:
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