Electronics I And Lab Models Introduction Week 6 Lab Is Base

Electronics I And Labac Modelsintroductionweek 6 Lab Is Based On The

Analyze the AC models of a transistor amplifier with a Q-point bias near the load line's center; design and implement the circuit on hardware and software, perform DC and AC analysis, measure voltages and currents, determine voltages such as VB, VE, VC, VBE, VCE, and the gain of the amplifier, troubleshoot faults, compare calculated and measured values, evaluate the role of capacitors in AC analysis, and document findings with screenshots and a comprehensive lab report.

Paper For Above instruction

The sixth-week laboratory exercise in Electronics I emphasizes understanding and analyzing AC models of a bipolar junction transistor (BJT) amplifier. The primary goal is to understand how biasing the transistor at a Q-point near the load line's middle allows for effective AC voltage amplification. This process involves both theoretical analysis and practical implementation on hardware and simulation software, culminating in detailed measurement, troubleshooting, and reporting.

Initially, students are guided to analyze the circuit illustrated in a provided schematic (Figure 1), focusing on calculating key voltages such as base (VB), emitter (VE), collector (VC), and the transistor's VBE and VCE. The calculations should consider component tolerances—typically ±20% for resistors and capacitors—and derive the voltage gain (AV) using the transistor's current beta value (assumed to be 100). The analytical process helps students understand the relationships between these parameters and the theoretical gain of the system.

The circuit construction follows the analysis phase, requiring students to assemble the specified BJT amplifier circuit on a breadboard using hardware components listed—such as a 2N3904 NPN transistor, resistors, and capacitors—and connect it properly to NI myDAQ instrumentation. The connections involve connecting a function generator to provide the input signal (Vin) at 1 kHz through channel AO0, supplying the VCC at +15V, and establishing measurement points for voltages and currents with multimeters and the NI instrument interface.

Subsequently, students perform a DC analysis by temporarily removing coupling capacitors to obtain steady-state voltages at various nodes, which are measured accurately with a multimeter and compared to initial calculations. Replacing the capacitors allows AC analysis, measuring the small-signal voltages at the base, emitter, and collector using the NI ELVISmx software and hardware. Loading effects are observed by measuring the load voltage (VRL) at the output, employing AI1 input for this purpose.

Between theoretical calculations and actual measurements, students compare the voltages, currents, and gain. The gain is determined experimentally from the input and load voltages and verified with the calculated value. Troubleshooting is integrated into the process; students download a troubleshooting guide, locate faults by measuring key points with an Agilent multimeter, and rectify issues. Post-repair measurements are documented to evaluate the effectiveness of fault correction.

A critical component of the lab involves addressing issues such as clipping in the collector current, which may occur due to improper biasing or power supply limitations. Adjustments to biasing components or supply voltages are made to eliminate clipping, ensuring the amplifier operates within its linear region. The role of capacitors in AC coupling and bypassing is analyzed, emphasizing their importance in maintaining signal integrity and gain stability.

The final phase involves comprehensive data logging—screenshots of waveform measurements from the function generator, oscilloscope, and multimeter readings—organized into tables for comparison. The collected data include temperature measurements, voltage nodes, and the calculated versus measured gain. Students prepare a detailed lab report using the provided template, embedding all necessary visuals, and submit it through the designated platform (Blackboard).

Throughout the lab, emphasis is placed on critical thinking, analytical skills, and precise measurement techniques. This exercise not only reinforces theoretical concepts such as biasing, AC amplification, and circuit analysis but also develops practical skills vital in electronic circuit design and troubleshooting. The comprehensive approach helps students bridge the gap between simulation and real-world applications, fostering a deeper understanding of transistor amplifier behavior.

References

  • Sedra, A. S., & Smith, K. C. (2015). Microelectronic Circuits (7th ed.). Oxford University Press.
  • Boylestad, R., & Nashelsky, L. (2013). Electronic Devices and Circuit Theory (11th ed.). Pearson.
  • Malvino, A. P., & Leach, D. P. (2007). Digital Principles and Applications. Tata McGraw-Hill Education.
  • Nguyen, T. A., et al. (2020). Practical Electronics for Inventors (3rd ed.). McGraw-Hill Education.
  • NI ELVISmx documentation. (2023). National Instruments. Retrieved from https://www.ni.com
  • Multisim User Guide. (2023). National Instruments. Retrieved from https://www.ni.com
  • Razavi, B. (2001). RF Microelectronics. Prentice Hall.
  • Johnson, D., & Graham, M. (2003). High-Speed Digital Design: A Handbook of Black Magic. Prentice Hall.
  • Horowitz, P., & Hill, W. (2015). The Art of Electronics (3rd ed.). Cambridge University Press.
  • Boylestad, R., & Nashelsky, L. (2016). Electronic Devices and Circuit Theory. Pearson.

Related Assignments