Work is done following the lab manual. There are parts of the lab involving building the actual circuit that do NOT need to be done, and these parts are crossed out. The simulation needs to be done in PartSim and coressponding data sheets in the excel file need to be filled out. Questions in the lab manual regarding the simulation need to be done. Models of transistors needed are attached as text file for the use in the simulation.
Operational Amplifier Circuits Page 1 McMaster University Electrical and Computer Engineering Department EE3EJ4 Electronic Devices and Circuits II - Fall 2021 Lab. 2 Single-Stage Amplifiers Lab Report Due on Oct. 10, 2021 Objective: To design and characterize the individual performance of a current sink, a common- emitter (CE) amplifier, and an emitter-coupled BJT pair (i.e., a differential amplifier) for their future combination to build an operational amplifier. Attributes Evaluated: These are the attributes you need to demonstrate in your solutions. • Competence in specialized engineering knowledge to simulate circuit performance using SPICE-based circuit simulator and conduct analog circuit debugging; • Ability to obtain substantiated conclusions as a result of a problem solution, including recognizing the limitations of the approaches and solutions; and • Ability to assess the accuracy and precision of results. Test Equipment: • Analog Discovery 2 (AD2) • WaveForms from Digilent Link • Analog Discovery 2 Quick Start Series Videos • WaveForms Reference Manual Components: • Transistors: 4 × NPN-BJT 2N3904 1 × PNP-BJT 2N3906 • Resistors: 2 × 8.25 kΩ resistor 2 × 76.8 kΩ resistor 2 × 57.6 kΩ resistor 2 × 8.06 kΩ resistor Transistors in the circuit: For a detailed description of these transistors, please check the following websites: https://www.onsemi.com/products/discretes-drivers/general-purpose-and-low-vcesat-transistors/2n3904 or https://www.onsemi.com/pub/Collateral/2N3903-D.PDF https://www.onsemi.com/products/discretes-drivers/general-purpose-and-low-vcesat-transistors/2n3906 or https://www.onsemi.com/pub/Collateral/2N3906-D.PDF Reminder: Switch off the DC power suppliers first whenever you need to change the circuit configurations. Switch on the DC power suppliers only when you do not have to change the circuit connection anymore. https://store.digilentinc.com/waveforms-download-only/ https://www.youtube.com/watch?v=HUAy0J3XqaU&list=PLSTiCUiN_BoLtf_bWtNzhb3VUP-KDvv91 https://reference.digilentinc.com/reference/software/waveforms/waveforms-3/reference-manual https://www.onsemi.com/products/discretes-drivers/general-purpose-and-low-vcesat-transistors/2n3904 https://www.onsemi.com/pub/Collateral/2N3903-D.PDF https://www.onsemi.com/products/discretes-drivers/general-purpose-and-low-vcesat-transistors/2n3906 https://www.onsemi.com/pub/Collateral/2N3906-D.PDF HW Cross-Out HW Cross-Out HW Cross-Out Page 2 Part 1: Common-emitter (CE) Amplifier Description of the CE Amplifier This lab would like to design a CE amplifier using a PNP-BJT 2N3096 with a constant current sink connected between its collector and the lowest power supply VEE. Due to the Early effect (as shown in Figure 6.18 of the textbook) of the transistor, the output current of the current sink changes with its collector voltage, which results in a finite output resistance Ro. Therefore, we usually model the current sink by an ideal current sink Io in parallel with its output resistance Ro. This output resistance Ro also serves as the AC load resistance for the AC signal from the transistor. This lab starts with the characterization of the output resistance Ro of a current sink, followed by the design of a CE amplifier. A. Pre-lab Simulation – Constant Current Sink 1.1 To characterize the output resistance of a current sink, construct the current sink in PartSim (or LTspice) with resistance values and supply voltages, as shown in Fig. 1. 1.2 DC Characteristics: Sweep VCC from -3.9V to -0.6V with 0.3V step and measure the emitter voltage VE and the collector IC. Record the simulated IC and VE in the sheet “Step 1.2” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”. 1.3 Output Resistance: For VCC higher than Vo,min, calculate the output resistance Ro of the current sink by CCo o VR I ∂ = ∂ , where Io is the collector current IC of Q1. Fig. 1 The schematic diagram for the constant current sink https://www.partsim.com/ https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html Page 3 B. Pre-lab Simulation – CE Amplifier 1.4 Construct the CE amplifier, as shown in Fig. 2, using a PNP-BJT 2N3906 and the current sink that we characterized in Fig. 1. Here Vsig provides the required DC bias for Q2 and the AC signal applied to the CE amplifier. 1.5 Quiescent (Q-) Point: Set the DC voltage of Vsig = 4.39V, measure the resulting DC voltage at Vo as Vo1. Set the DC voltage of Vsig = 4.41V, measure the resulting DC voltage at Vo as Vo2. Record the measured Vo1 and Vo2 in the sheet “Step 1.5” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”. 1.6 DC Characteristics: Sweep the DC voltage of Vsig, from 4.39 V to 4.41 V with 0.1 mV step. Measure the collector current IC2 and the voltage Vo at the collector of Q2. Record the simulated IC2 and Vo in the sheet “Step 1.6” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”. Find the Vsig = VBQ2 that results in Vo ≈ 0V. 1.7 Frequency Response: Set the DC value of Vsig = VBQ2 and the AC amplitude of Vsig = 1 mV, conduct AC analysis for Vo in DEC with Start Frequency = 100 Hz, Stop Frequency = 1 MHz, and Total Points Per Decade = 101. Choose REAL for magnitude unit and degree (DEG) for phase unit. Record the measured |Vo| and ∠Vo in the sheet “Step 1.7” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”. Fig. 2 Schematic diagram of the common emitter (CE) amplifier Page 4 C. In-lab Measurement – Constant Current Sink 1.8 Use the port definition diagram of AD2 shown in Fig. 3 when setting up your experiments. 1.9 Based on Fig. 1, construct the measurement setup for the constant current sink. Use Wavegen 1 (W1) for VCC and V- for VEE. Connect Scope Ch. 1 Positive (1+) to VB (the base of Q1) and Scope Ch. 2 Positive (2+) to VE (the emitter of Q1). Connect GNDV+, GNDV-, Scope Ch. 1 Negative (1-), and Scope Ch. 2 Negative (2-) to a common ground 1.10 DC Characteristics: Start WaveForms program, click Workspace, open the provided script function workspace file “Lab2_Step1.10.dwf3work”, and press Run. This script sets V- = -5V, sweeps Wavegen 1 (W1) from -3.9V to -0.6V with 0.3V voltage step, and measures the base voltage VB and the emitter voltage VE of Q1. Click on the Script tag, select all data in the Output window, and right-click to save them into a text file “Lab2_Step1.10.txt”. 1.11 Run Excel and open the text file “Lab2_Step1.10.txt”. Choose Delimited as the file type, Comma in Delimiters, and General in Column data format to import the data. The first row is the VCC data, the second row is the VB data, and the third row is VE data, respectively. 1.12 Copy the whole data in a row, right-click the destination cell in the sheet “Step 1.10” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”, choose Paste Special from the context menu, and select Transpose to record the measured VB and VE. It calculates the output current Io, which equals the collector current IC1 of Q1 as follows. V B BR V VI R R − = = −1 1 1 0 , (1) ( ) V VBB EE BR VV V VI R R R − −− + = = =2 2 2 2 5 5 , (2) B R RI I I= −1 1 2 , (3) ( ) V VEE EE EE VV V VI R R R − −− + = = =1 3 3 3 5 5 , (4) and o C E BI I I I= = −1 1 1 . (5) 1.13 Keep the constant current sink connected. We will use it again in Part D when designing a common-emitter (CE) amplifier. HW Cross-Out Page 5 Fig. 3 Diagram for the port definition of an Analog Discovery 2 (AD2) D. In-lab Measurement – CE Amplifier 1.14 Based on Fig. 2, construct the measurement setup for the common-emitter (CE) amplifier. Use V+ = 5V for VCC, V- = -5V for VEE, and Wavegen 1 (W1) for Vsig. Connect GNDV+, GNDV-, and GNDW1 to a common ground line. 1.15 Connect Scope Ch. 1 Positive (1+) to Wavegen 1 (W1), Scope Ch. 2 Positive (2+) to Vo (the collector of Q2). Connect the Scope Ch. 1 Negative (1-) and Scope Ch. 2 Negative (2-) to the common ground. 1.16 DC Characteristics: In WaveForms, click Workspace, open the provided script function workspace file “Lab2_Step1.16.dwf3work”, and press Run. This script sweeps the DC voltage of Wavegen 1 (W1) from 4.38 V to 4.40V with 1 mV step and uses Voltmeter in WaveForms to measure the output voltage from W1 and the corresponding voltage Vo at the collector of Q2. Record the W1 setting, measured Vsig, and Vo values in the sheet “Step 1.16” of the Excel file “Lab 2 – Single-Stage Amplifier.xlsx”. Find the DC voltage VBQ2 of Wavegen 1 (W1), which results in Vo ≈ 0V. 1.17 Quiescent (Q-) Point: Connect Scope Ch. 1 Positive (1+) to VB (the base of Q1) and Scope Ch. 2 Positive (2+) to VE (the emitter of Q1). Set W1 to the VBQ2 obtained in Step 1.16. Use Voltmeter in WaveForms to measure the base voltage VB and the emitter voltage VE of Q1. Record the measured VB and VE in the sheet “Step 1.17” of the Excel file “Lab 2 – Single-Stage HW Cross-Out Page 6 Amplifier.xlsx”, which calculates the collector current IC2 = IC1 using (1) to (5). 1.18 Connect Scope Ch. 1 Positive (1+) to Wavegen 1 (W1), Scope Ch. 2 Positive (2+) to Vo (the collector of Q2). In WaveForms, Channel 1 (W1) window, set Type = Sine, Frequency = 100 Hz, Amplitude = 1 mV, Offset = VBQ2 from Step 1.16, Symmetry = 50% and Phase = 0°. 1.19 Using Scopes: Display the measurement results using the Scope function in WaveForms. In Scope 1, set Channel 1 with Offset = –VBQ2 and Range = 1 mV/div to see the input waveform. For Channel 2, set Offset = 0 V and Range = 1 V/div. Use Y Cursors to set their upper and lower peak values and use the Ref function to calculate the difference. Record the measured amplitude of Scope Ch. 1 Positive (1+) and Scope Ch. 2 Positive (2+)