Academic Year 2023/24 M21388 Introduction to Analogue Circuits Coursework2 Deadline for Submission: Return Marked Work by: Submission Instructions: UNIVERSITY OF PORTSMOUTH FACULTY OF TECHNOLOGY Teaching Block 2 (MP3 Headphone Amplifier) There are two coursework assignments for this module. This is the second coursework of this module for Teaching Block 2 and represents 25% of the unit mark. Cuhmiccion data CWTROL Janhavn Mandla Instructions for completing the assessment: Please submit a report (in PDF format) covering both Sections 1 and 2. Please upload your full source files (.asc for LTspice or .ms14 for Multisim). Your source files must be ready for simulation so please test them before submission. Examiner: Overview of the Coursework 2 for Teaching Block 2 Coursework 2 described in this document is divided into two sections. The first section (Section 1 - Investigation of operational amplifier circuits) has four simulation experiments involving operational amplifiers, designed to reinforce the theory covered during the lectures. The second section (Section 2 - Project to design an MP3 headphone amplifier) is a project in which you will be required to design a circuit to meet a given specification and requirements. Working practices You should work individually and complete the coursework independently. Although the Multisim simulation software can be used for the coursework, the LTspice simulator is strongly recommended because this simulator is free and is therefore not restricted by license issues. LTspice has been selected as the main tool to be used throughout the module, and it will be used in other modules too. All work including circuit analysis and design, theoretical calculation (prediction), simulation analysis and evaluation and lab experiments should be shown in the report. You are encouraged to seek advice and obtain feedback on what you have already done at any, and preferably on several occasions. The marks and the feedback on the report will be given within 20 working days after the deadline of submission. Please submit ONLY ONE PDF report which covers all your work. All simulation source files should be uploaded along with the report. The source files should be ready for simulation. Please be warned that the plagiarism detection software Turnitin will be used on your submission. Mock submissions before the submission deadline are allowed to check the similarity rate. You should write the report using your own words to reduce the similarity rate. The similarity rate of your report should be below 20%. 2023-2024 Page 1 of 10 - Section 1 – Investigation of Operational Amplifier Circuits Experiment 1: Inverting Amplifier The purpose of this experiment is to build and investigate one of the two most common operational amplifier circuits. You should be able to reconcile and reinforce what you are learning in lectures. The pin configuration of the operational amplifier is shown in Fig. 1 and its pin functions are shown in Table 1. NAB Package 8-Pin CDIP or PDIP Top View OFFSET NULL-1 8-NC INVERTING INPUT 2 7-V+ NON-INVERTING 3 6 OUTPUT INPUT V-4 5 OFFSET NULL Fig. 1 Pin configuration of LM741 (courtesy of the Texas Instruments) Table 1 Pin Functions of LM741 (courtesy of the Texas Instruments) PIN 1/0 DESCRIPTION NAME INVERTING NO. 2 | Inverting signal input INPUT NC 8 N/A No Connect, should be left floating NONINVERTING 3 | Noninverting signal input INPUT OFFSET NULL 1,5 | Offset null pin used to eliminate the offset voltage and balance the input voltages. OFFSET NULL OUTPUT 6 Amplified signal output V+ V- 7 | Positive supply voltage 4 I Negative supply voltage The circuit diagram of an inverting amplifier circuit is shown in Fig. 2 below. The input signal (generated by a function generator) is a 3 kHz sine wave with an amplitude of 0.25 V. The positive supply voltage of the operational amplifier is 15 V and the negative supply voltage is -15 V. Please note that circuit diagrams for op-amp circuits generally don't show power supply connections (Pins No. 4 and No. 7 for LM741) but these should be included in simulation and in real circuits to ensure the circuits operate normally. 10ΚΩ www 2023-2024 VIN O 1ΚΩ www Fig. 2 An inverting amplifier. VOUT Page 2 of 10 Tasks for Experiment 1: • • • • Connect a load resistor between VOUT and the ground. Select a standard value (greater than 10 k) for the load resistor. Calculate the theoretical voltage gain (VOUT/VIN) of the circuit. Build up the circuit in the LTSpice simulator. Complete the simulation analysis and capture the waveforms of the input voltage signal VIN and the output voltage signal VoUT of the circuits. • Compare the input and the output signals and explain the results. • What is the measured and theoretical value of gain (show calculations)? Investigate what happens at high frequencies (gradually increase the frequency and look for attenuation and distortion). Describe the manner in which attenuation changes with frequency. Describe the distortion you observe at high frequencies. Capture a waveform to illustrate this. . Keeping the amplitude of the input constant, measure the amplitude of the output voltage in the LTspice at the following frequencies: 10Hz, 100Hz, 1kHz, 5kHz, 10kHz, 20kHz, 30kHz, 40kHz, 50kHz. Tabulate your results. . • Keeping the amplitude of the input constant, measure the amplitude of the output voltage in the lab at the following frequencies: 10Hz, 100Hz, 1kHz, 5kHz, 10kHz, 20kHz, 30kHz, 40kHz, 50kHz. Tabulate your results. What is the input impedance of this amplifier circuit? What are the implications of this result? Evidence required in your report for the assessment of Experiment 1 • Title of your investigation. • Description of your investigation (what did you do). • Circuit diagram built in the simulator. • Photos of the circuits built for the lab experiments. • Captured waveforms via the simulator and in the lab. Discussion of results. This must fully explain your findings. Full source files ready for simulation (submitted along with the report). • The simulation results obtained via LTspice should agree with the measured results in the lab. If not, please find out the reasons and correct mistakes (if there are any) in your simulation and/or in the lab experiments. Marking scheme for Experiment 1 [Total 10 marks]: • The theoretical voltage gain is correctly obtained. [1 mark] The circuit is correctly built up in LTspice and the simulation results are correct. [2 marks] • The circuit is correctly built up on a breadboard. [1 mark] • The input and the output voltage signals are correctly measured. [2 marks] • The output voltage amplitudes at the specified frequencies are correctly measured in LTspice and in the lab. [2 marks] • The input impedance of the amplifier circuit is correctly determined. [2 marks] 2023-2024 Page 3 of 10 Experiment 2: Non-inverting Amplifier The purpose of this experiment is to build and investigate the other one of the two most common operational amplifier circuits. You should be able to reconcile and reinforce what you are learning in lectures. The circuit diagram of the non-inverting amplifier is shown in Fig. 3. The positive supply voltage of the operational amplifier is 15 V and the negative supply voltage is -15 V. The input signal (generated by a function generator) is a 3 kHz sine wave with an amplitude of 0.3 V. VIN www -OVOUT www R₂ Fig.3 A non-inverting amplifier. Tasks for Experiment 2: • • • Connect a load resistor between VOUT and the ground. Select a standard value (greater than 10 k) for the load resistor. If R1 has a resistance value of 2 k and the voltage gain of the circuit is 12, please determine the theoretical value of R2 (show calculations). Please build up the circuit in the LTspice simulator and verify your design. Please build up the circuit in the lab and verify your design. Capture the waveforms of the input signal and the output signal of the circuits in the LTspice and in the lab. • What is the input impedance of this amplifier circuit? What are the implications of this result? Evidence required in your report for the assessment of Experiment 2 Title of your investigation. Description of your investigation (what did you do). Circuit diagram built in the simulator. • • • Photos of the circuits built for the lab experiments. • Captured waveforms via the simulator and in the lab. • Discussion of results. This must fully explain your findings. Full source files ready for simulation (submitted along with the report). • The simulation results obtained via LTspice should agree with the measured results in the lab. If not, please find out the reasons and correct mistakes (if there are any) in your simulation and/or in the lab experiments. Marking scheme for Experiment 2 [Total 10 marks]: The theoretical value of R2 is correctly obtained. [2 marks] • The circuit is correctly built up in LTspice and the simulation results are correct. The circuit is correctly built up on a breadboard. [2 marks] [2 marks] • The input and the output voltage signals are correctly measured. • The input impedance of the amplifier circuit is correctly determined. [2 marks] [2 marks] 2023-2024 Page 4 of 10