Abstract:

The situation with the COVID-19 Pandemic has posed new challenges for university professors around the world when developing sets of e-learning tools that allow students to carry out research resembling experiments carried out in university laboratories as closely as possible. Mastering of the material related to Op Amps requires practical work on their implementation, use of measuring instruments such as generators and oscilloscopes as well as subsequent processing of the measurement results.

The use of the free version of the NI Multisim Analog Devices Edition software environment provides the opportunity to create models for the simulation of the parameters of a wide variety of circuits with Op Amps using virtual measuring instruments. The circuits created and the experimental settings can be reconfigured easily using switches.

The authors of this article share their experience in teaching disciplines in the field of analog electronics. The simulation models which were developed and examined allow the lecturers to set individual assignments for each student, and the students to independently conduct the research for each assignment. This research precedes the experiments students carry out using the models available in university laboratories.

Op Amps are present in the production of key units in electronics, communications and industry. In the process of designing and verifying devices implemented with Op Amps, a number of simulation procedures and laboratory experiments are combined, with the aim of creating lasting knowledge, which is a prerequisite for the design of new circuits and devices.

The authors of the article have developed a set of electronic tools (simulation circuits and educational videos) for the study of the static parameters and the dynamic characteristics of Op Amps.

The report presents a model for using a simulation to determine the DC parameters of the operational amplifiers LM 741CH (National Semiconductor) and OP07CH (Linear Technology), namely: Input Offset Voltage (Uio), Input Bias Current (IiB), Input Offset Current (Iio). It was created in Multisim as this environment provides a measuring probe to perform circuit analysis in all nodes and branches during the simulation.

The simulation values for the main parameters of the Op Amps which were examined are tabulated and compared with their catalogue counterparts. An analysis was performed of the results obtained.

The report presents models for using a simulation to determine basic dynamic characteristics and parameters of integrated Op Amps VFA (Voltage Feedback Amplifier): transmission, amplitude-frequency characteristics (voltage gain), phase-frequency characteristics, gain bandwidth product / width - GBW, slew rate - SR. The results obtained are presented in tabular and graphical form and are analyzed.

The proposed simulation models, accompanied by specially created educational videos and used for conducting simulation research allow the students to use them at any time and anywhere, which results in the improved motivation of the students when studying the content.

The developed models and the research conducted with them, presented in the article, have been tested in the online training of students during the COVID-19 lockdown in the discipline "Analog electronics" in the specialties "Computer and Communication Systems" and "Hardware and Software Systems" at the Faculty of Physics and Technology of Plovdiv University "Paisii Hilendarski".

Keywords:

Online teaching, simulation models, educational videos, static parameters, dynamic characteristics, Op Amps.