Assessment Brief
Programme:
BEng/MEng Electrical and Electronic Engineering
Module Code:
KD4014
Module Title:
Research, Analysis and Presentation
Distributed on:
31 Oct 2024
Submission Time and Date:
19/12/2024 by 16:00 GMT
Word Limit:
8-12 pages (Font size 11)
Weighting
This coursework accounts for 50% of the total mark for this module
Submission of Assessment
Electronic Management of Assessment (EMA): Please note if your assignment is submitted electronically it will be submitted online via Turnitin by the given deadline. You will find a Turnitin link on the module’s eLP site.
It is your responsibility to ensure that your assignment arrives before the submission deadline stated above. See the University policy on late submission of work.
Instructions on Assessment (Important to read):
Students are expected to undertake:
• Individual Laboratory Report: You are required to submit a well-structured, word-processed laboratory report based on the simulation of the audio amplifier circuit.
• Literature Review: Conduct a literature review focusing on the background and applications of the audio amplifier circuit to provide context and depth to your report.
• ORCAD Simulation Results: Include detailed ORCAD simulation results (including PCB design) in your report, ensuring that all required graphs and data are presented clearly.
• Analysis and Discussion: Provide a comprehensive discussion and analysis of how varying parameters affect the performance of the audio amplifier circuit as observed in your simulations.
Additional Instructions to Students:
• Simulation Practice: Do not rush through the simulation exercises as adequate time has been allocated for practice.
• Procedural Compliance: Completion of the laboratory session is mandatory, and results should be recorded in a Word document.
• Report Submission: Your report should be concise, with a target length of 8 to 12 pages, not exceeding 12 pages. The final report must be submitted electronically via the e-learning portal by the deadline of 19th December 2024.
• Graphical Representation: All graphs (with properly labelled axes, units, legends, and data points) must be generated using OrCAD, Excel, Matlab, Gnuplot, or any other suitable software. Figures and waveforms must be created digitally—handwritten, photographed, or scanned documents will not be accepted.
Further Information
Learning Outcomes assessed in this assessment:
1. Describe and illustrate the understanding of science and engineering principles using a range of verbal, written and graphical techniques when researching and analysing real world problems.
2. Demonstrate certain level engineering simulation skills.
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3. Analyse, interpret and present data obtained from simulation work with knowledge of the software implementation.
4. Demonstrate knowledge and understanding of engineering principles and methodology through engagement with simulation work and by using them to analyse engineering processes.
Assessment Criteria/Mark Scheme:
No
Item
Marks (%)
1.
Introduction and simulation tools
(AHEP4 C4)
Introduction and applications of audio amplifier circuit with measurement and evaluation of the performance
10
Investigation and discussion of the key features of OrCAD (e.g. simulation analysis types and applications)
10
2.
Results and discussion
(AHEP4 C9, M9, C12, M12)
Part A – Graphs and analysis of the outputs in volt and dB (AC sweep analysis)
10
Part B – Graphs and analysis of the input and output waveforms in time-domain (transient analysis)
15
Part C – Recorded gains in the table and the discussion on the relationship of R3 and Gains
15
Part D – Design and discussion of a PCB for the audio amplifier circuit using LM386
20
3.
Conclusion
10
4.
Formatting and style of the report
(AHEP4 C17)
10
Total
100
(50% weighting)
Marks Breakdown:
1. Introduction and Simulation Tools (Marks: 0-20): This section should provide a thorough introduction to the audio amplifier circuit, including an overview of its applications, key characteristics, and features. A detailed review of different types of audio amplifier circuits should be included, along with methods for measuring and evaluating their performance. Additionally, this section should introduce the OrCAD simulation software, discussing its key features and different types of simulation analyses (e.g., AC sweep, transient analysis). Marks will be awarded for clear and concise discussions, and a comprehensive summary of the audio circuit features and OrCAD's capabilities.
2. Results and Discussion (Marks: 0-60): This section is crucial for assessing the student's practical work in the lab sessions using OrCAD. It should include the implementation of the circuit in the simulation tool, following the basic procedures accurately. Marks will be awarded based on the correctness and accuracy of the simulation results, the clarity of the presentation of graphs and tables, and the depth of the discussion on the findings. The breakdown is as follows:
• Part A (10 marks): Graphs and analysis of the outputs in volts and dB using AC sweep analysis.
• Part B (15 marks): Graphs and analysis of the input and output waveforms in the time domain using transient analysis.
• Part C (15 marks): Recorded gains in a table and a discussion on the relationship between R3 and Gains.
• Part D (20 marks): Design and discussion of a PCB for the audio amplifier circuit using LM386.
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3. Conclusion (Marks: 0-10): This section should provide a concise summary of the work conducted on the simulation of the amplifier circuit. The student should make a clear summative statement reflecting on the implementation of the circuit and the key observations from the simulation results.
4. Formatting and Style (Marks: 0-10): This section assesses the overall presentation quality of the report, including the use of English, the structure and organization of the report, the inclusion of contents pages and bibliography (optional), and the use of summaries and advance organizers. Additionally, marks will be awarded for the effective page layout, the clear presentation of figures and charts, and correct referencing throughout the document.
Bloom’s taxonomy for this assignment (domain and verbs relevant examples using the 2001 revised model)
Domain
Verbs
Create
Design, Create, Invent
Evaluate
Select, Critique, Defend
Analyse
Organise, Examine,
Apply
Use, Demonstrate, Sketch
Understand
Describe, Explain, Discuss
Remember
Memorise, List, State
Assignment weighting:
This assignment is worth 50% of the module marks
Referencing Style:
If you need to use any references please do so and reference them using an appropriate style (ideally IEEE or similar numerical style)
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Laboratory: Audio Amplifier Circuit using LM386
1. Objective: The objectives of the workshop are
(i) to implement the audio amplifier circuit using LM386 in OrCAD;
(ii) to study the performance of the circuit using AC sweep and time-domain analysis in OrCAD
(iii) to investigate the frequency response of the amplifier in the audio signal process;
(iv) to measure the waveform and amplification of the audio amplifier circuit;
(v) to design a PCB for the audio amplifier circuit using LM386 in OrCAD PCB editor
2. Equipment Required:
• 1 x Personal Computer with Windows OS
• Cadence OrCAD Lite (version:17.2)
3. Location:
Laboratory: C103
4. Background information to read:
At the centre of the circuit is an audio amplifier Integrated Circuit or IC. Inside the IC are many transistors, which are connected together to allow the small input signal to be amplified into a more powerful output that can drive a speaker. The ability of the amplifier to increase the power or amplitude of a signal from the input to the output by adding energy, converted from some power supply, to the signal is called the gain. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It is often expressed using the logarithmic decibel (dB) units ("dB gain"):
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 𝐺𝐺𝐺 𝐺𝐺𝐺𝐺 (𝑑𝑑𝑑𝑑)=20log 􁉀𝑉𝑉𝑜𝑜𝑜𝑜𝑜𝑜𝑉𝑉𝑖𝑖𝑖𝑖􁉁 (1)
All amplifiers usually need to use negative feedback to ensure the amount of gain stays constant. This allows the output to be an exact copy of the input, only larger. Figure 1 shows the circuit diagram of the audio amplifier using LM386.
Figure 1: Circuit diagram of the audio amplifier using LM386 (Texas Instruments).
An amplifier will have a bandwidth suited to the range of frequencies it is intended to amplify. Too narrow a bandwidth will result in the loss of some signal frequencies, and too wide a bandwidth will allow the introduction of unwanted signals. In the case of an audio amplifier for example these would include low frequency hum and perhaps mechanical noise, and at high frequencies, audible hiss.
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In that respect the amplifier becomes a filter and the bandwidth is given by the -3 dB line as shown in Figure 2.
Figure 2: A graph of a bandpass filter's gain magnitude, illustrating the concept of −3 dB bandwidth. For a graph plotting voltage gain this corresponds to a voltage reduction of 􀶥𝟏𝟏/𝟐𝟐 or half the power.
5. Simulation/PCB design Procedures:
The main objective of the assignment for lab sessions is to study the performance of LM386 Audio Power Amplifier using Cadence OrCAD Lite as shown in Figure 3. LM386 is power amplifiers designed for use in low voltage consumer applications. This study enables the learners to gain the knowledge of circuit analysis on the commercial power amplifier and how the performance of circuit to the human audio frequency from 20Hz to 20kHz.
(1) Follow the schematic in Figure 3 to create a project named ‘KD4014_LM386_XXXX (your student ID)’ You can find details regarding the “Create a project” and ‘Add Library’ in the Section 7.2 and Section 7.3.1, Fig 7.10 and Fig 7.11 of the module handbook.
(2) Simulate the circuit to obtain the frequency response of the circuit with the parameters defined and obtained in Task (1). Plot the amplitude of the output voltage in volt and dB as a function of input frequency. Indicate and write down the cutting-off frequency (drop of -3 dB in gain), where the gain
Figure 3: Schematic of the audio amplifier circuit using LM386
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in volt is a half of the value at frequency of 20kHz. The logarithmic x-axis range should be between 20Hz and 20kHz.
(You can find details regarding the “AC sweep” analysis in the Section 7.3.5 and Figure 7.22 of the module handbook.)
Use the following settings for the “AC Sweep” simulation:
Analysis type: AC Sweep / Noise
AC Sweep Type: Logarithmic - Decade
Start Frequency: 20
End Frequency: 20k/1000k
Points/Decade: 10
Describe the obtained plots and discuss how to find out the bandwidth of this audio amplifier.
(3)
Simulate the circuit in Figure 4 using the OrCAD and PSpice to obtain the transient response of the circuit with the parameters defined in the diagram.
R1=8, R2=10, R3=1.2k,
C1=10u, C2=250u, C3=1u,C4=1n, C5=0.047u,C6=0.1u,C7=10u
V1=9,
V2: Use the VSIN/SOURCE component as the 0.01 Volts sinusoidal input voltage (Vin) with the following parameters:
VOFF = 0; VAMP = 0.01; FREQ = as specified in Table I.
(You can find details regarding the “Transient (Time Domain)” analysis in the Section 7.3.6 of the module handbook. The schematic diagram of the associated circuit for transient analysis is shown in Figure 3)
Obtain four different figures showing the amplitude of the input and output voltages (on the same plot) as the functions of time for different frequencies of input voltage, as shown in Table I:
Table I
FREQ of Vin
x-axis range
Figure 1:
25 Hz
1.0s - 1.2s
Figure 2:
250 Hz
1.0s - 1.02s
Figure 3:
2500 Hz
1.0s - 1.002s
Use the following settings for the “Time Domain (Transient)” simulation:
Analysis type: Time Domain (Transient)
Run to time: 1.2s/1.02s/1.002s (according to the frequency)
Figure 4: OrCAD capture CIS schematic for Transient response of the circuit
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Maximum step size: 5u
And record the actual voltage Gain and Gain in dB for each figure using the following equation:
Gain=Vout(peak)/Vin(peak) 𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 𝐺𝐺𝐺 𝐺𝐺𝐺𝐺 (𝑑𝑑𝑑𝑑)=20log 􀵬𝑉𝑉𝑜𝑜𝑜𝑜𝑜𝑜𝑉𝑉𝑖𝑖𝑖𝑖􀵰
The peak value of the input and output can be obtained in the waveforms. Discuss what you have observed from these waveforms.
(4) Change the value of R3 to 1, 100, and 500 respectively, calculate the gains at the different input frequencies as shown Table 1. Summarise the results in a table and then discuss the relationship of R3 and Gain. Also, adjust the value of C1 (e.g. 0.1u, 1u or 100u) to see any changes in the output.
(5) PCB Design and Analysis
Present the final PCB layout in the layout and discuss the following questions:
• What considerations did you take into account when placing components on the PCB and
How did you determine the appropriate trace widths for different signals? Provide calculations and reasoning.
• Discuss the trade-offs between a single-layer and a double-layer PCB in the context of this design and what are the potential impacts of your design choices on the manufacturability and cost of the PCB?
The following are instructions on the PCB design
Step 1: Update the schematic (OrCAD CIS Capture)
1. Schematic update: Replace the components V1 and V2 in Figure 4 as two components of ‘jumper’ P1 and P2, which are used as the interface for the power supply and input signals in PCB design.
2. Footprint assignment: Open the property settings to assign the appropriate footprint to each component.
Step 2: Generate the Netlist (OrCAD CIS Capture)
1. Create the Netlist: After completing the schematic, generate the netlist by selecting Tools > Create Netlist. Choose OrCAD PCB format and configure the options according to your PCB design requirements.
2. Save the Netlist: Save the netlist in your project folder.
Step 3: Setting Up the PCB Layout in OrCAD PCB Editor
1. Launch PCB Editor: Open OrCAD PCB Editor and create a new board file.
2. Import the Netlist: Import the netlist generated in Step 2 by selecting File > Import > Logic. This will bring all the components and connections into the PCB layout environment.
3. Define the Board Outline: Use the Outline tool to define the dimensions of the PCB board according to your design requirements.
4. Place Components: Arrange the components on the PCB board manually by dragging them from the imported netlist. Ensure that the placement minimizes trace lengths and adheres to design for manufacturability (DfM) principles.
Step 4: Routing the PCB
1. Set Design Rules: Before routing, set up design rules such as trace width, clearance, and via sizes by selecting Setup > Constraints > Spacing.
2. Manual Routing: Begin routing the connections between components manually by selecting Route > Connect. Start with critical signals such as power and ground lines, then proceed with other signal traces.
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3. Ground Plane Creation: Create a ground plane by using the Shape > Rectangle tool to draw a copper pour connected to the ground net.
4. Run DRC: After routing, run the Design Rule Check (DRC) to ensure there are no violations in your PCB layout.
Step 5: Finalizing the PCB Design
1. Place Vias and Silkscreen: Add vias where necessary, and ensure the correct placement of silkscreen elements (e.g., component labels, reference designators).
2. Check for Errors: Perform a final DRC to check for any remaining errors or design rule violations.
3. Generate Gerber Files: Once the PCB design is complete, generate the Gerber files by selecting File > Manufacture > Artwork. These files are necessary for the manufacturing of the PCB.
ASSESSMENT REGULATIONS
You are advised to read the guidance for students regarding assessment policies. They are available online here.
Late submission of work
Where coursework is submitted without approval, after the published hand-in deadline, the following penalties will apply.
For coursework submitted up to 1 working day (24 hours) after the published hand-in deadline without approval, 10% of the total marks available for the assessment (i.e.100%) shall be deducted from the assessment mark.
Coursework submitted more than 1 working day (24 hours) after the published hand-in deadline without approval will be regarded as not having been completed. A mark of zero will be awarded for the assessment and the module will be failed, irrespective of the overall module mark.
These provisions apply to all assessments, including those assessed on a Pass/Fail basis.
The full policy can be found here.
Word limits and penalties
If the assignment is within +10% of the stated word limit no penalty will apply.
The word count is to be declared on the front page of your assignment and the assignment cover sheet. The word count does not include appendices, glossary, footnotes or tables.
Please note, in text citations [e.g. (Smith, 2011)] and direct secondary quotations [e.g. “dib-dab nonsense analysis” (Smith, 2011 p.123)] are INCLUDED in the word count.
Students must retain an electronic copy of this assignment (including ALL appendices) and it must be made available within 24hours of them requesting it be submitted.
The full Word Limit Policy is available here.
Academic Misconduct
The Assessment Regulations for Taught Awards (ARTA) contain the Regulations and procedures applying to cheating, plagiarism and other forms of academic misconduct.
The full policy is available at here
You are reminded that plagiarism, collusion and other forms of academic misconduct as referred to in the Academic Misconduct procedure of the assessment regulations are taken very seriously. Assignments in which evidence of plagiarism or other forms of academic misconduct is found may receive a mark of zero.

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