SPICE Demo Circuits and Netlists: Come Up To Speed Quickly on Your Schematic

The old joke is, “How do you get to Carnegie Hall? Practice!” Well I’ve been to Carnegie Hall, and all I had to do was buy a ticket. But the point is that as with most everything in our lives, we must practice to improve our skills in order to excel at what we are doing. Even the simple things in life are improved with practice. If you’ve never juggled before, just try tossing three raw eggs in the air at the same time and you will quickly see what I mean.

Everyone understands the need for CAD skills in circuit design in order to create schematic library parts, place components, and connect the nets. But there is also another part of circuit design, that if used on a regular basis, can help our engineering efforts to a great degree. This is using Simulation Program with Integrated Circuit Emphasis (SPICE) tools to simulate the behavior of electronic circuits.

It will be pretty tough to get good results if you were to just jump into a SPICE simulation session for the first time without a little practice first. Here are some of the SPICE basics that you will come to understand after spending a little more time working with SPICE demo circuits and netlists.

Why You Need SPICE Demo Circuits and Netlists

Simulation is an important part of circuit design. At one time circuit validation was done through building breadboards to physically model your circuits. Although this is still an effective method for circuit development, the circuitry that you most likely will be working with today is far too complicated for physical models.

Working with breadboards is very limiting in its time, expense, and the depth of testing that you can do. Simulating your circuits through design software however can resolve all of those problems. Additionally, simulating your circuits with SPICE will also reduce or eliminate the need for multiple PCB board spins that once was a requirement for circuit validation.

There are many different versions of SPICE that you can work with, and there are a variety of tutorials, demo circuits, and netlists available as well. Some simple online searches can reveal a host of SPICE information. After spending time practicing with some of these resources, you will be better prepared to use SPICE for your regular production work.

Electronic design engineering can be greatly helped by simulating circuits with SPICE

What You Can Expect from These Tools

Let’s take a look at some of the basic building blocks that you will be working with in SPICE tools:

• Schematics: Circuits to be simulated can be captured graphically using a schematic capture application. The schematic will contain SPICE models for the components in use as well as the connectivity between the component pins. All of this SPICE information can also be created in a netlist text file without the schematic. The advantage of using a working with a SPICE tool within a schematic capture application is that you will be combining both tasks into one tool.

• SPICE Models: SPICE simulation information for components are contained in text descriptions called models. This data is then used by the SPICE engine to simulate mathematically the behavior of the component in a circuit. When working with a schematic this model information is associated with its corresponding component symbol. Depending on whether the component is simple or complex, the amount of data in a model can range from one line of text to hundreds. Often model information is offered with specific schematic capture and SPICE tools, or it can be downloaded from the component manufacturers.

• SPICE Commands: When working with a schematic, all instructions entered into SPICE application will create a corresponding text command in the final SPICE netlist. These commands are for configuration of the simulation, executing the simulation, and generating the simulation results.

• SPICE Netlists: All of the SPICE data that is collected in the schematic is generated into one netlist file for the SPICE simulation engine. The netlist could also be generated manually as long as the correct format for models, connectivity, and commands are followed.

• Simulation: The SPICE simulation engine runs through the netlist and captures all of the model and connectivity information, and then executes the netlist commands on the data. The SPICE simulation engine will then generate the requested outputs to report circuit performance back to the user.

Now that we’ve talked a little about how SPICE works, let’s look at how it can help you to be more productive in your design work.

PSpice from Cadence is a great productivity enhancer for your design work

With the Right Tools, You Can be More Productive

With all the different versions of SPICE available to work with, you need to work with the one that can help you the most. This will include everything from its features and options to available models and from demo circuits and netlists to ease of use. To be the most effective it is best if the SPICE tools you are using are integrated with your PCB design system.

Having your SPICE tools integrated in the PCB design system removes the need to work with interfaces and translators so that the two tools can work together in the same environment. With the two tools working together, you can spend more time creating and testing your circuits instead of moving and matching data files from one system to another.

From your first practice sessions with SPICE demo circuits and netlists to using these tools to regularly test and validate your PCB designs, you need SPICE software that you can depend on. PSpice, from the Cadence family of PCB design tools, has a long history of being the go-to solution for design engineers. PSpice is fully integrated into the Cadence schematic capture tools and is feature rich with its features and capabilities.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.