Multisim7, as one of many simulation software, is applied in the teaching of electrical and electronic technology, which challenges the current teaching mode. Because of its powerful function and convenient teaching application, the software is showing an unlimited application space to educators in its unique way. This paper mainly discusses the definition, development process, functional characteristics of EDA Simulation and its role in teaching, and discusses the existing shortcomings.

1. What is EDA simulation

EDA is the abbreviation of electronic design automation. It is a simulation tool based on VHDL. It is a general software package of electronic CAD developed on the basis of computer as the working platform and integrating the latest achievements of electronic technology, computer technology and intelligent technology. It can be used to describe the design idea of analog circuit and digital circuit layer by layer from the upper layer to the lower layer (from abstract to concrete), and to represent the extremely complex circuit system with a series of hierarchical modules. Therefore, it can mainly assist in IC design, electronic circuit design and PCB design.

2. The development of EDA

From the development of EDA, it has experienced three historical stages. The first stage is CAD technology in 1970s, the second stage is CAE Technology in 1980s, and the third stage is EDA Technology in 1990s. EDA technology is the latest development direction of 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 achieve various stages of electronic circuit design: modeling, simulation, verification and synthesis. In this series of steps, simulation experiment is an essential part of teaching. In this part, all kinds of circuit data and waveform parameters can be reflected at a glance. Therefore, it is now widely used in the experimental teaching of electrical and electronic.

3. Implementation of hardware description language VDL

Hardware description language (HDL) is an important part of EDA technology. As the mainstream hardware description language of electronic design, VHDL (vhsi hardware description language) has the characteristics of being independent of specific hardware circuit and design platform, and has good ability of circuit behavior description and system description. It has good performance in language readability and hierarchical design It has strong vitality and application potential. Therefore, VHDL has shown good adaptability in supporting design methods of various modes, top-down and bottom-up or hybrid methods, and in the face of the shortening of the life cycle of many electronic products nowadays, it needs to be redesigned many times to integrate the latest technology and change the process. Its biggest 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.

Analysis of the definition, development process, functional characteristics and role of electronic EDA simulation

4. Functions and characteristics of EDA simulation

Multisim7 is one of the well-known EDA software. Its predecessor is EWB5.0. With the outstanding advantages of visual interface, convenient operation, easy to learn and use, and powerful simulation analysis function, Multisim7 is favored by electronic design and educators, and has been rapidly promoted and applied. Its functions are as follows:

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

Multisim7 provides a large number of real components and virtual components for the user’s system, which are stored in 13 device libraries. When drawing the circuit diagram, you only need to open the device library, then select the component to be used with the left mouse button, and drag it to the work area. When the light mark moves to the pin of the component, the software will automatically generate a black dot with a cross, and enter the work area Connection status, click the left button to confirm, move the mouse to achieve connection, and establish the circuit diagram is convenient and fast.

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

Users can connect virtual instruments in circuit diagram to test circuit performance parameters and waveforms conveniently. There are 18 kinds of virtual instruments provided by Multisim7 software, such as digital multimeter, dual trace oscilloscope, function signal generator, baud diagram generator, frequency meter, etc. These instruments not only have the same appearance and use method as the actual instruments, but also measure more accurate and reliable values and waveforms, which fully achieve the purpose of the experiment.

Multiple types of simulation analysis

Multisim7 can be used for DC operating point analysis, AC analysis, transient analysis, Fourier analysis, noise analysis, distortion analysis, DC scanning analysis, parameter scanning analysis, sensitivity analysis, transfer function analysis, batch processing analysis, noise graphic analysis and RF analysis, etc. the analysis results can be displayed directly in numerical or waveform form, which provides a reference for users to design analysis circuits It’s very convenient.

4.4 provides the interface of information exchange with other software

Multisim7 can be opened by pspic. And other circuit simulation software. Grid table file, and automatically form the corresponding circuit diagram. It can also convert the circuit diagram established by Multisim7 into grid table file and provide it to ultiboard module or other EDA software (such as Protel, OrCAD, etc.) for automatic layout and routing of printed circuit board diagram.

It is necessary to spend too much time and energy on process related factors that do not affect the function.

5. Application of muultisim7 in Teaching

5.1 rich learning resources and powerful teaching function

Because Multisim7 builds a huge component library module, the component quilt is divided into three groups in Chengdu, and each component library module contains different number of component families. Common component families include: power supply components, basic components, diode components, triode components, integrated circuit components, CMOS circuit components, digital miscellaneous components, etc. All of these components create sufficient conditions for modeling of various types of circuits. Whether it is the demonstration and experiment of electrician foundation, analog electronic technology or digital electronic technology, it can be done through modeling (placing components and completing circuit connection), selecting voltage or waveform test points, placing test instruments, running simulation analysis and other steps (for example, the simulation results are not consistent with the design values, The parameters of components should be readjusted until the simulation results are consistent with the design values.

Therefore, the measurement of voltage and waveform at each point of the circuit and the qualitative analysis of AC and DC parameters can be realized. In the process of simulation, all levels of design can be expanded to understand and master more knowledge, such as the name, type, performance parameters and functions of components. In the circuit measurement, open the library of instruments and meters, the instrument will also have all the knowledge and understanding, greatly enrich the amount of information not in books.

5.2 break the original teaching mode and realize the synchronization of theory and practice teaching

In the teaching of the course, due to the limitation of the laboratory and experimental instruments, under the condition of multimedia teaching, the simulation experiment can be carried out in the classroom. The simulation effect can attract students’ attention most, and can timely show the empty theory and various invisible parameter values, voltage values and actual waveforms, and give the voltage and signal clearly The characteristics and changing process of the system. It solves the teaching mode that the combination of theoretical preaching and experiment can be carried out simultaneously, eliminates the students’ doubts about the conclusion in time, achieves one-step in place, and makes the understanding of knowledge more profound and firm.

5.3 it is convenient to mobilize students’ learning enthusiasm and creativity

Because of its powerful function, complete component library and sufficient types of instruments, this software seems to provide students with an inexhaustible, inexhaustible and no consumption of strong economic support. As long as students have inspiration and creative spirit, they can design the circuit by themselves, and can verify whether their design is correct, reasonable and achieve the design purpose through experiments in time. So as to improve students’ interest in learning and stimulate their desire for scientific and technological innovation, and better cultivate high skilled talents with innovation ability.

6. The deficiency of Multisim7 in Teaching

Multisim7 has many advantages, but it also has some disadvantages

6.1 lack of physical reference, it is difficult to improve students’ practical ability

Because the design of the circuit is based on VHDL language, and the virtual component symbols replace the physical objects, there is no actual operation in the whole process of the experiment. In this way, there are some deficiencies in the cultivation of students’ practical ability, and it is unable to train the students’ operating procedures.

6.2 it is too idealistic to cultivate students’ mentality of how to face complex factors and environment

Because the design of the components is based on the ideal parameters, and is not affected by any external factors, so the measured data results do not have errors, often the experiment can be successful at one time. In the actual test or experiment, due to the different external conditions and factors, the change of parameters is inevitable, so it is necessary to adjust the data more than once, adjust the test repeatedly, and sometimes there will be failure results. Therefore, the application of simulation software is disadvantageous to the cultivation of students’ rigorous and scientific attitude.

To sum up, EDA simulation technology, as a teaching means, is applied to teaching, not losing its advanced nature. It not only effectively changes the teaching form, enriches teaching content, improves teaching efficiency, but also plays a subtle role in cultivating students’ autonomous ability and creating imagination ability. But we have to 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 the application of multimedia teaching, EDA technology will play a role in promoting the teaching reform, and will be more perfect at the same time.

Editor in charge: Tzh

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