Analysis of NPN Transistor Laboratory: Part 6, Lab Reports of Electrical and Electronics Engineering

Download Analysis of NPN Transistor Laboratory: Part 6 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! ECE 3254 Name Analysis of NPN Transistor Laboratory #6 Partners: PRELAB Bench: Read over the entire Lab 6. Show all work (equations, values, etc) for credit. 1. On the curve trace below, label the three operating regions of a transistor. Describe the characteristics of each region (think in terms of the relationships between IC, IB, β, VCE & VBE). (15 points) 2. Using the active model (where Ic = β*IB) with VCC=15V, VCE = 6V, and IC = 10mA, find the value of RC and determine the equation to find RB for the circuit given in Figure 6-1. NOTE: RB will be an equation that is a function of β. Enter the results below and on Part II-1 of the Data Sheet. (20 points) Hint: Use a KVL loop for the base circuit (VCC/RB/VBE) and a KVL loop around the collector circuit (VCC/RC/VCE) to start. ECE 3254 Lab 6 Page 1 of 7 3. See the prelab notes about the small signal AC transistor model. Apply the small signal model to the circuit in Figure 6-2 and derive the equations needed to solve for the passband voltage gain, AV = Vo/Vs. Assume that the DC source VCC is bypassed to ground for AC signals. NOTE: rπ will be a variable in your equation. Enter the results below and on Part III-1 of the Data Sheet. Hint: Remember that rπ (near 500Ω) in parallel with RB (>150kΩ) can be simplified as ~rπ. Solve for ib as a function of VS, solve for VO as a function of ib, and combine the results. (25 points) Use the AC small signal model to derive the flow cutoff frequency equation for the amplifier input circuit. (This will be a function of rπ). Hint: remember that rπ (near 500Ω) in parallel with RB (>100kΩ) can be simplified as ≈rπ.Enter the results below and on Part III-2 of the Data Sheet. Hint: the input circuit is very similar to Lab 3. (20 points) Use the AC small signal model to derive the flow cutoff frequency equation. Enter the results below and enter the frequency on Part III-2 of the Data Sheet. Hint: You can use a Thevenin to Norton transformation and change the dependent current source with a parallel Rc into an equivalent dependent voltage source with a series Rc to make the circuit resemble Lab 3. (20 points) ECE 3254 Lab 6 Page 2 of 7 2. Use the small signal model cutoff frequency equations to calculate the high pass cutoff frequency flow for the input and output circuits. Enter the results on the Data Sheet. 3. Use the computer to make an AC sweep measurement of the amplifier's frequency response from 1Hz to 1kHz with 45 data points and a 0.1Vpp sinusoidal input signal. Save the AC sweep response as a jpeg file. Normalize the response to 0.1Vpp. Use the red cursor to indicate dBmax (maximum passband output response) and the blue cursor to indicate the cutoff frequency flow (3 dB down from max). Record the measured passband gain and the cutoff frequency on the Data Sheet. Print the frequency response jpeg. Title your print, label the cutoff frequency, passband, and dBmax, write your name on the print, and attach the print to your Data Sheet. 4. Shut down Windows, return cables to racks, return parts to correct drawer bins, return adapters to container, turn off bench power, clear bench, and place seat under bench. (5 points) ECE 3254 Lab 6 Page 5 of 7 ECE 3254 Lab 6 Data Sheet Name_____________________ Date______________ Partner ________________ Bench_________ PART I: BJT DC Analysis 3. RB = __________ VRC = VCC - VCE = _________ VRB = VCC-VBE = __________ VBE = ________ IC = __________ IB= __________ β = IC/IB = __________ 4. RB = __________ VRC = VCC - VCE = _________ VRB = VCC-VBE = _________ VBE = ________ IC = __________ IB= __________ IC/IB = _________ (≠β) PART II: BJT BIAS DESIGN (DC) 1. From the Prelab: RC = Equation from the Prelab: RB = Calculated RB = ____________ Calculated RC = ____________ 2. Q-point measurements and circuit component values. Calculated Actual/Measured VCE 6V _____________ IC 10 ma _____________ (use VCE to calculate IC) RB __________ _____________ RC __________ _____________ How do your measured IC and VCE compare to the design values? What is responsible for the differences between the measured values and the expected values? 3. Calculated rπ =____________ ECE 3254 Lab 6 Page 6 of 7 PART III: BJT AC ANALYSIS 1. Equation from the Prelab: Vo/Vs = Calculated Vo/Vs = _____________ = _________dB Measured Vs = _______Vpp Vo = ________Vpp Output phase = __________ Measured Vo/Vs = __________ = _________dB How closely does the measured gain match the predicted gain? (NOTE: If you are not in the ballpark, troubleshoot your circuit.) 2. Equations from the Prelab: Input flow = Output flow = Calculated Input flow = _____________ *Output flow = _____________ 3. Measured passband gain = ________dB (normalized to Vi = 1Vpp) Measured cutoff frequency flow = ________ Hz How do the measured values of Gain and flow compare to your calculations? Explain what might be responsible for differences. ECE 3254 Lab 6 Page 7 of 7