Experiment5Report - EEE3007C­0011 Electronics 1 Lab Monday...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EEE3007C­0011 Electronics 1 Lab Monday 9:00 ­ 11:50 AM Experiment #5 Transistor Small­Signal Amplifiers By: Due Date: March 21, 2016 Objective: The objective of this experiment is to study small­signal transistor amplifiers. This study was conducted using common collector (CC), also known as the emitter follower, and common emitter (CE) configurations, along with variations of the two. Equipment: ● ● ● ● ● ● ● Oscilloscope: Tektronix DPO 4034 Digital Oscilloscope Function Generator: Tektronix AFG3022 Dual Channel Function Generator Power Supply: Agilent E3630A 2N2222 Bipolar Transistors Breadboard Capacitors available in the laboratory Resistors available in the laboratory Figure 1, above, shows the circuit design of a common emitter amplifier configuration. Figure 2, above, shows the circuit design of the common collector amplifier, or emitter follower, configuration. Introduction: In our continuing study of transistors, applications of them such as amplifying methods are of great interest. Two such methods of amplification are studied in detail in this set of experiments: the common emitter and and common collector transistor amplifiers. Pre­Lab: As stated in the lab manual, the values to be used in the circuit shown in Fig. 1 are: V​ = 12V, R​ = 6.2kΩ, R​ = 1.8kΩ, R​ = 2.2kΩ, R​ = 1.8kΩ, and C​ = 100µF. CC ​ C ​ E ​ L ​ S​ E​ Common Emitter Amplifier: With C​ : E​ Without C​ : E​ 1. In order to reach the desired I​ (≈ 1 mA) and maintain good bias stability, R​ and R​ CQ​ 1​ 2 were calculated to be 121.65kΩ and 35kΩ, respectively. 2. Using these values for R​ and R​ , the Q­point was calculated to be (4V, 1mA), and the 1​ 2​ maximum unclipped output voltage equal to 1.62V. 3. Using formulas provided in the lab manual, the small signal voltage gains were calculated to be A​ = ­62.45 and A​ = ­40.88. Vi​ Vs​ 4. The input and output resistances, R​ and R​ , respectively, can be calculated using the I​ O​ equations given in the lab manual. The result of these calculations is R​ = 3410Ω and R​ I​ O = 5838Ω. 5. Repeating step 2 with capacitor C​ removed from the circuit, results in a Q­point of (4V, E​ 1mA) and a maximum unclipped output voltage of 3.42V. Repeating step 3 with C​ E removed results in small signal voltage gains A​ = ­3.14 and A​ = ­3.37. Repeating step Vi​ Vs​ 4 with C​ removed results in R​ = 24740Ω and R​ = 6200Ω. E​ I​ O​ Emitter Follower Amplifier: Repeating steps 1­4 of the common emitter amplifier, this time in reference to Figure 2: 1. In order to reach the desired I​ (≈ 1 mA) and maintain good bias stability, R​ and R​ CQ​ 1​ 2 were calculated to be 121.65kΩ and 35kΩ, respectively. 2. Using these values for R​ and R​ , the Q­point was calculated to be (10.2V, 1mA), and the 1​ 2​ maximum unclipped output voltage equal to 0.99V. 3. Using formulas provided in the lab manual, the small signal voltage gains were calculated to be A​ = 0.99 and A​ = 0.92. Vi​ Vs​ 4. The input and output resistances, R​ and R​ , respectively, can be calculated using the I​ O​ equations given in the lab manual. The result of these ​ calculations is ​ RI​ ​ = 24700Ω and R​ = 36.2Ω​ . O​ The next step was to confirm the calculated results a​ bove, using computer simulation. Figure 1.1.0 The above figure shows that the design has allowed for I​ = 1.04 mA, which is very CQ​ close to the desired value. Figure 1.2.0 The above figure confirms the calculated Q­point, with the simulated results providing (3.64V, 1.04mA). Figure 1.3.0 This figure shows the simulated results for A​ . With V​ = 20mV and V​ = 864.55mV, VS​ S​ O​ the gain is equal to ­43.2 in simulation. Figure 1.3.1 The above figure shows the simulated result for V​ = 14.2 mV. Knowing that V​ = I​ O​ 864.55mV, A​ is calculated to be ­60.88. Vi​ Figure 1.4.0 The above figure uses V​ = 20mV as a test source, dividing it by I​ = 4.45 μ A (shown in S​ S​ the graph) results in input resistance, R​ = 4.5kΩ. I ​ Figure 1.4.1 The same process was used to find the output resistance R​ . I​ was found to be 3.42 μ A, O​ S​ using V​ = 20mV, as a test sourse, R​ = 5.85kΩ. S​ O ​ Figure 1.5.0 After removing capacitor C​ , simulation showed I​ = 587nA. R​ was found to be equal to E​ S​ I ​ 27.3kΩ. Figure 1.5.1 Again, with C​ removed from Figure 1, simulation results provided I​ = 3.2 μ A, resulting E ​ S​ in R​ = 6.25kΩ. O​ Figure 2.1.0 In the design of Figure 2, our calculate values were confirmed by simulation, with I​ = CQ​ 1.048 mA. Figure 2.2.0 The simulated Q­point resulted in (10.1V,1.048mA). Figure 2.3.0 The results of Figure 2.3.0 show that V​ = 18.1mV, V​ = 18.5mV, and the source, V​ = O​ I​ S​ 20mV. Simulation results show A​ = 0.978 and A​ = 0.905. Vi​ Vs​ Figure 2.4.0 Using a test source V​ = 20mV, and dividing it by its current, I​ = 824nA resulted in a S​ S​ simulated R​ = 24.3kΩ. I​ Figure 2.4.1 The same test source was used in finding R​ . The simulation resulted in I​ = 659 μ A, and O​ S​ R​ = 30Ω. O​ Experiment: In order to determine the validity of the theoretical results, a set of experiments was performed for each of the same amplifiers as Figures 1 and 2e conditions as the corresponding simulations. using C​ = 10 μ F, C​ = 10 μ F, C​ = 10 μ F, and a sinusoidal 5 kHz signal. Additionally, the same B​ 1​ E​ values for all of the components within each system were used as in the pre­lab. The small­signal voltage gains A​ and A​ (Figures 2.1­2.2 & 2.4­2.5), voltages v​ and v​ , and the output voltage vs​ vi​ s​ i​ for R​ connected and disconnected (Figures 2.3 & 2.6) were measured. Furthermore, the input L​ resistance ( peak vpeak (v −v ) s −vi ) and output resistance ( RL ovL L RL ) were calculated based off of these measurements. These results are summarized in Table 1. Figure 2.1 shows the signal used for measuring A​ for the common emitter circuit vs​ Figure 2.2 shows the signal used for measuring A​ for the common emitter circuit vi​ Figure 2.3 shows the signal used for measuring v​ without R​ for the common emitter circuit o​ L​ Figure 2.4 shows the signal used for measuring A​ for the common collector circuit vs​ Figure 2.5 shows the signal used for measuring A​ for the common collector circuit vi​ Figure 2.6 shows the signal used for measuring v​ without R​ for the common collector circuit o​ L​ Conclusion: In conclusion, the results of the experiment and theory are generally in good agreement. Any discrepancies are likely due to differences in the value for β due to sensitivity to manufacturing methods of a given transistor. We have seen differences here between the common emitter and common collector transistor amplifiers such as a clear difference in the sign on the gain as well as a much lower output resistance and higher input resistance for the emitter follower circuit than for the common emitter. It is also clear, based off of experiment, that R​ affects the output L​ voltage of the common emitter circuit far more than for the common collector. These differences cast light on methods in which the characteristics for each of these circuits can be manipulated to suit the user. Furthermore, it is very apparent that these two circuit types have nearly­opposite characteristics, making it useful to understand the merits of each when deciding to use a transistor­amplifier circuit. Experimental Measurement Common Emitter (Fig. 1) Common Collector (Fig. 2) A​ vs ­40.8 0.84 A​ vi ­60 0.9 v​ s 10 mV 17.6 mV v​ i 6.5 mV 16.4 mV Input Resistance 3343 Ω 24.6 k Ω v​ with R​ o​ L 400 mV 14.8 mV 1.6 V 16 mV 6930 Ω 178 Ω v​ without R​ o​ L Output Resistance Table 1 gives a comprehensive summary of experimental results for each circuit configuration. References: th​ Microelectronics­Circuit Analysis and Design, D. A. Neamen, McGraw­Hill, 4​ Edition, 2007, ISBN: 978­0­07­252362­1 ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern