The idea of simulating electronic circuits is not new and has existed for over 60 years. The SPICE simulation was developed in the 1960s at the University of California, Berkeley. The acronym SPICE stands for Simulation Program with Integrated Circuit Emphasis. The principle of SPICE is based on solving nonlinear systems of equations describing components and circuits. Of course, possibilities, algorithms, and simulation models have been further optimized since the 1960s. SPICE is fundamentally text-based and describes component properties and their interconnection.
The SPICE simulation with Multisim
The next logical step in the development of the SPICE simulation was the graphical abstraction for the user. This is where the Multisim development environment comes in. Formerly known as Electronics Workbench, Multisim was acquired by National Instruments in 2005 and has been developed and maintained ever since. Multisim is used in education and teaching, such as universities, colleges, or vocational and technical schools, as well as in research and industrial development for the simulation of circuits of analog and digital technology.
Industrial customers come, for example, from device development, test equipment construction, automotive, research, medical technology, or the military. NI Multisim includes a database of components from leading semiconductor manufacturers such as Analog Devices, National Semiconductor, Linear Tech, and Texas Instruments, and offers mixed-mode simulation. With this feature, both analog and digital components can be simulated in combination. In the first step of the circuit development, it may be useful to evaluate the component behavior, to decide as to which component with its specific characteristics for the respective task is most likely in question.
The virtual instruments in Multisim
When the required components have been placed in Multisim and wired, the task is to examine the circuit. The tool offers the possibility, in particular through “virtual instruments,” to investigate circuits based on really quickly and intuitively. For this, measuring instruments such as function generator, 2-channel and 4-channel oscilloscope, multimeter, Bode plotter, spectrum analyzer, current clamps, and much more are available. The virtual measuring instruments offer the possibility to investigate circuits without many configurations – as is usual in reality. With the frequency generator, for example, the input signal of an amplifier circuit could be generated and visualized with the oscilloscope, the output signal.
Once the necessary performance and functionality of the circuit have been verified, the analysis is available for further investigation as needed. By using the standard SPICE analysis technology, detailed benchmarks and characteristics, such as the passband of a filter or the study of harmonics, can be created. Analyzes such as AC analysis, Fourier analysis, noise analysis, worst-case analysis, Monte Carlo analysis are available. All these options allow a variety of “what-if” scenarios to be played comfortably on the PC. What happens when the tolerances of the components used multiply? How does the cutoff frequency of my amplifier circuit behave when using a different opamp type?