As one of many simulation software, MulTIsim7 is used in the teaching of electrical and electronic technology, which poses a challenge to today's teaching mode. Because of its powerful functions and convenient teaching application, the software is showing an infinite application space to educators in its unique way. This paper mainly discusses the definition, development process, functional characteristics and role of EDA simulation in teaching, and discusses the existing problems.

1. What is EDA simulation

EDA is the abbreviation of English Electronic Design AutomaTIonr, that is, electronic design automation. It is a simulation tool built on the basis of the hardware description language VHDL. It refers to a general-purpose electronic CAD software package successfully developed by taking the computer as the working platform and integrating the latest achievements in the application of electronic technology, computer technology and intelligent technology. Using it, the design of analog circuits and digital circuits can be described layer by layer from the upper layer to the lower layer (from abstract to concrete), and a series of hierarchical modules can be used to represent extremely complex circuit systems. Therefore, it can mainly assist in IC design, electronic circuit design and PCB design.

2. The development history of EDA

From the perspective of the development of EDA, it has gone through three historical stages. The first stage is the CAD technology in the 1970s, the second stage is the CAE technology in the 1980s, and the third stage is the electronic design automation system in the 1990s, that is, the current EDA technology. EDA technology is the latest development direction of today's electronic design technology. It not only provides "top-down" design ideas for electronic designers, but also provides a very convenient and scientific experimental teaching platform for teaching work. Because, for electronic designers, it can be used to realize various design stages of electronic circuits: modeling, simulation, verification and synthesis. In this series of steps, the simulation experiment is an essential and important part of teaching. In this part, various data and waveform parameters of the circuit can be clearly reflected. Therefore, it is now widely used. Applied in the experimental teaching of electrical engineering.

3. Implementation of hardware description language V-DL

Hardware description language is an important part of EDA technology. VHDL (VHSICHardwareDescripTIonLanguage) is a description language for mainstream hardware in electronic design. It is characterized by characteristics that are independent of specific hardware circuits and design platforms. The ability of system description, and in terms of language legibility and hierarchical design, shows strong vitality and application potential. Therefore, VHDL supports various modes of design methods, top-down and bottom-up or mixed methods, in the face of the shortening of the life cycle of many electronic products today, it needs to be redesigned many times to dissolve the latest technology and change the process. and other aspects have shown good adaptability. Its greatest advantage is that the designer can concentrate on the realization of its function without spending too much time and energy on the process-related factors that do not affect the function.

4. Features of EDA simulation

MulTIsim7 is one of the well-known EDA software. Its predecessor is EWB5.0. This software has outstanding advantages such as intuitive interface, convenient operation, easy to learn and use, and powerful simulation analysis functions. It is highly favored by electronic designers and educators. And get the rapid promotion and application. Its functions are:

4.1 It is convenient and quick to establish a circuit schematic diagram

Multisim7 provides a large number of real components and virtual components for the user system, which are stored in 13 device libraries. When drawing a circuit diagram, you only need to open the device library, and then use the left mouse button to select the components to be used. Drag and drop it to the work area, when the cursor moves to the pin of the component, the software will automatically generate a black dot with a cross, enter the connection state, click the left button to confirm, and move the mouse to realize the connection. It is convenient and fast to build circuit schematic diagram.

4.2 Using virtual instruments to test circuit performance parameters and waveforms is accurate and intuitive

Users can connect virtual instruments in the circuit diagram to easily test the performance parameters and waveforms of the circuit. There are 18 types of virtual instruments provided by the Multisim7 software, such as digital multimeters, dual trace oscilloscopes, function signal generators, and Bode plots. generator, frequency meter, etc. These instruments are not only the same in appearance and use as the actual instruments, but also the measured values ​​and waveforms are more accurate and reliable, which fully achieves the purpose of the experiment.

4.3 Various types of simulation analysis

Multisim7 can perform DC operating point analysis, AC analysis, transient analysis, Fourier analysis, noise analysis, distortion analysis, DC sweep analysis, parametric sweep analysis, sensitivity analysis, transfer function analysis, batch analysis, noise graph analysis and RF Analysis, etc., the analysis results are displayed intuitively with numerical values ​​or waveforms, which provides great convenience for users to design analysis circuits.

4.4 Provides an interface for exchanging information with other software

Multisim7 can be opened by PSpic. Spic created by other circuit simulation software. grid table file, and automatically form the corresponding circuit schematic. It can also convert the circuit schematic diagram created by Multisim7 into a grid table file, and provide it to the Ultiboard module or other EDA software (such as Protel, Orcad, etc.) for automatic layout and automatic routing of printed circuit board diagrams.

Excessive time and effort needs to be spent on process-related factors that do not affect functionality.

5. Application of Muultisim 7 in teaching

5.1 Rich learning resources and powerful teaching functions

Since Multisim 7 builds an extremely large component library module, the component quilt is divided into 3 urban groups (Group), and each component library module contains a different number of component families (Family). Commonly used component families: power components, basic components, diode components, triode components, integrated circuit components, CMOS circuit components, digital miscellaneous components, etc. These various components create sufficient conditions for the modeling of various circuits. Whether it is the demonstration and experiment of electrical engineering, analog electronic technology, and digital electronic technology, you can model (place components, complete circuit connections), select Steps such as voltage or waveform test points, placement of test instruments, and running simulation analysis (if the simulation results do not match the design values, the component parameters should be re-adjusted until the simulation matches the design values).

Therefore, it can realize the measurement of the voltage and waveform of each point of the circuit and the qualitative analysis of the AC and DC parameters. In the simulation process, the design at all levels can expand the understanding and master more knowledge, such as the names, types, performance parameters and functions of components. When measuring the circuit, open the instrument library, and you will have all the knowledge and understanding of the instrument, which greatly enriches the amount of information that is not available in books.

5.2 Break the original teaching mode and realize the synchronization of theoretical and practical teaching

In the course teaching, because it is not limited by laboratories and experimental instruments, under the condition of multimedia teaching, simulation experiments can be carried out in the classroom. And various parameter values, voltage values ​​and actual waveforms that are invisible and intangible are vividly displayed, and the characteristics and changing processes of voltage and signals are clearly given. It solves the teaching mode in which theoretical lectures and experiments can be carried out synchronously, eliminates students' doubts about the conclusion in a timely manner, and achieves one step in place, and the understanding of knowledge is more profound and firm.

5.3 It is easy to mobilize students' learning enthusiasm and creativity

Due to the powerful functions of this software, the complete component library and the sufficient types of instruments and meters, it seems to provide students with an inexhaustible and inexhaustible strong economic support without consumption. Students can design circuits by themselves as long as they have inspiration and creative spirit, and can verify whether their designs are correct and reasonable through experiments in a timely manner, and whether they achieve the design goals. In order to improve students' interest in learning and stimulate their desire for scientific and technological innovation, it can better cultivate high-skilled talents with innovative ability.

6. The shortcomings of Multisim7 in teaching

Multisim7 has many advantages, but there are also shortcomings, which are mainly reflected in the following aspects:

6.1 Lack of physical reference, it is difficult to improve students' practical ability

Since the design of the circuit is based on the VHDL language, and the virtual component symbols are used to replace the real object, there is no actual operation in the whole process of the experiment. In this way, the training of students' hands-on ability is obviously insufficient, and it is impossible to train students in operating procedures.

6.2 Too idealistic, it is difficult to cultivate students' mentality on how to face complex factors and environments

Since the design of the components is all calculated with ideal parameters and is not affected by any external factors, there is no error in the measured data results, and the experiment is often successful once. In the actual test or experiment, due to the difference of various external conditions and factors, the change of parameters is unavoidable. It is necessary to adjust the data more than once, repeat the adjustment test, and sometimes fail. Therefore, the application of simulation software is not conducive to cultivating students' rigorous scientific attitudes that are not afraid of setbacks.

To sum up, the application of EDA simulation technology in teaching as a teaching method is not lost on its advanced nature. It not only effectively changes the teaching form, enriches the teaching content, improves the teaching efficiency, but also helps to cultivate students' autonomy. Ability, creative imagination, have played a subtle role. However, we must realize that EDA simulation is only one of the many means to assist teaching. How to use it to serve the teaching process more effectively has put forward higher requirements for today's educators. We also believe that with the popularization and deepening of multimedia teaching applications, EDA technology will play a role in promoting teaching reform, and it will also be more perfect.
Responsible editor: tzh

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