Common-Emitter Amplifier
EEL 3304C –Design and Experiment Project Lab # 4 Common-Emitter Amplifier 1.
Objectives
This project teaches the design of a BJT amplifier. The use of simulation (via PSpice) as an integral part of the design methodology methodo logy is also emphasized. 2.
Equipment
You will need the following • 2N2222A NPN BJT Suppl y • 6255A Power Suppl • National Instruments Elvis • Textronix TDS2024 DSO • Various capacitors and resistors. 3.
Design and Experiment Protocol st
3.1 Pre-lab (PSPICE Simulation) to be done prior to 1 week of lab (Week 1)
Read and understand Chapter 5 on BJT fundamentals (through Chapter 5.4). (1) Read datasheet for the NPN 2N2222A transistor to find typical, min, and max values for β at IC = 15 mA and VCE = 5 V. Assignment: Print and bring copy of datasheet. (2) Simulate the large-signal common-base characteristics using the following circuit in PSPICE.
In PSPICE, plot IC (y-axis) versus versus VCB (x-axis) as a function of IE using a nested DC sweep. Use a range of -1V to +10V for VCB and 0 to 30 mA with a 5 mA increment for IE. Assignment: Print and bring original copy of schematic and probe plot .
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Common-Emitter Amplifier
(3) Simulate the large-signal common-emitter characteristics using the following circuit in PSPICE.
In PSPICE, plot IC (y-axis) versus versus VCE (x-axis) as a function of IB using a nested DC sweep. Use a range of 0V to +10V for VCB and 0 to 100 uA with a 10 uA increment for IB. Assignment: Print and bring original copy of schematic and probe plot .
3.2 BJT parameter measurements (Week 1)
(1) Use the curve tracer to measure IC versus VCB. Include at least 5 curves corresponding corresponding to different IE and indicate IC, VCB, and IE values used to measure α. Sketch the IC versus VCB curves in your your laboratory notebook. What is the difference between the large signal signal α and the incremental α? (See Section 5.2.2. on page 398.) (2) Use the curve tracer to measure IC versus VCE. Include at least 5 curves corresponding to different IB (VBE) and indicate IC, VCE, and IB values used to measure β. Sketch the IC versus VBE curves in your laboratory laboratory notebook. What is the the difference between the large signal β and the incremental β? (See Section 5.2.4. on page 402.) Measure β at IC = 15 mA and VCE = 5 V for two 2N2222A transistors. transistors. Pick one β and the corresponding BJT for the design below. below. Save the BJT for the experiment in week 2. (3) Practice biasing the BJT BJT in active mode using four four resistor biasing. Choose a collector current, IC, that is within the operating specs of the 2N2222A and design using available resistors and a single 15V power supply. Verify that the the 2N2222A is in active mode.
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3/24/06
Common-Emitter Amplifier 3. 3 Pre-lab (Design of Experiment) to be done prior to 2nd week of lab (Week 2) Read and understand Chapter 5.5 – 5.7 on single-stage BJT amplifiers.
Design Specifications: Using the common-emitter nd configuration shown, (before 2 week of lab) design an amplifier with the following specifications: Vout = 2 Vp-p; Pout = 1 mW into R L ; VCC = 15 V; signal source: Vsig = 50 mVpeak @ 10 kHz in series with R sig sig = 50 Ω; V bePK < 10mV. Hints: /3 drop across RC and - Let V CC CC V CE CE . - Find RC from V oPk
1 V Rc =
Rc // R L
3 Rc
.
[background: V bePk bePk
