What Is a Circuit Diagram?

The circuit diagram ^[1] refers to a circuit connection symbol represented by a circuit element symbol. The circuit diagram is a principle layout diagram showing the composition of various components and the relationship between devices for the needs of research and engineering planning. From the circuit diagram, you can learn the working principle between components, and provide planning solutions for analyzing performance and installing electronic and electrical products. In designing the circuit, the engineer can easily do it on paper or on a computer, and confirm the perfection before performing the actual installation. Improve through debugging, fix errors, and succeed. Using circuit simulation software for circuit-assisted design and virtual circuit experiments can improve the efficiency of engineers, save learning time, and make the physical map more intuitive.

The circuit diagram is mainly composed of four parts: component symbols, connections, nodes, and comments. ^[2]

Circuit diagram has

Connection physical map

1. If it is a series circuit, connect from the positive pole of the power supply to the negative pole of the power supply in a certain order, and connect whatever it encounters until it is completed;

2. If it is a parallel circuit, you can take the method of splitting to complete-divide the circuit into several circuits, and then complete the connection one by one;

3. It should be noted ^[1]

1. If it is a series circuit, draw in a certain order from the positive pole of the power supply to the negative pole of the power supply, and draw whatever it encounters until it is completed;

2. If it is a parallel circuit, you can use the method of splitting to complete-divide the circuit into several circuits, and then complete the connection one by one; if it is a parallel circuit, also pay attention to the intersection and the connected points should be described with obvious black points ^[3]

From Protel to Altium

As long as you are engaged in electronics, you know PROTEL ^[2] , just as you know the Windows operating system as long as you use a computer. This is because many of its operating habits have been rooted in the hearts of electronic people. PROTEL is CAD software for the circuit industry launched by PORTEL (now Altium) in the late 1980s. It deserves to be ranked in front of many EDA software and is the software of choice for circuit designers. It was used earlier in China and has the highest penetration rate. It is used by almost all circuit companies.

From the original PCB design tools in the DOS environment to the now powerful AltiumDesigner, Altium has launched many different versions. As far as I know, the more commonly used versions are as follows:
PROTEL99SE: Although it is an early version, many companies are still using it, we are using it, and some companies only recognize this version of the file. Almost 10 years later, comrades, you know the power of habits!
PROTEL2004SP4: In 2002, Altium released PRTELDXP. In addition to some enthusiasts who tried it early, others still held PROTEL99SE and some people even refuse to let it go. After all, there are still many new features that attract new users. When you have to change versions, many people may directly use the latest version of PROTEL2004 at that time. After the addition, the version is no longer named after PROTEL. Many people use This version is a PRETEL commemorative work. When opening new types of files that PROTEL99SE cannot open, this second-class classic version is used.
AltiumDesigner6.8: In 2005, Altium officially released AltiumDesigner6.0. Since then, the era of PROTEL has ended. Until 2007, AltiumDesigner 6.8 was released, which is the latest version. I believe a lot of people haven't used it much, but there should be many people to try it first. It is said that the software integrates all the technologies and functions required for the integrated development of electronic products. A unified application for electronics engineers and designers. These include plate system design, FPGA-level system design, embedded software development based on FPGA and discrete processors, PCB layout, editing and manufacturing. And integrated into modern design data management functions. Previously released tools such as P-CAD are gradually integrated into AltiumDesigner after 2006. However, I do not particularly agree with this approach. The circuit design is mainly used in the schematic and PCB design. The rest of the miscellaneous functions are upset. And after all there are more professional tools OrCAD and CADENCE

OrCAD and CADENCE

ORCAD is EDA software introduced by ORCAD company in the late 1980s ^[4] . Many people are not unfamiliar with it, claiming to be the best tool for drawing circuit schematics, but because the software uses software dog anti-piracy, it is not popular in China and its popularity is not comparable to PROTEL.
Similarly, there is also a PCB tool that is said to be the best to use, which is Allegro of CADENCE, I have also used it, and I think it is really easy to use.
However, there is better news. Later, CADENCE acquired ORCAD, which can be described as a strong alliance. Later, ORCAD and ALLEGO can also perform interaction design. For users, this is nothing but a good thing. Therefore, many people use ORCAD (later called DesignEntryCIS) for schematic design, and ALLEGO for PCB layout design, to achieve the best partner. Many textbooks are also introduced in this way.
Of course, after all, ORCAD and ALLEGO are not brothers. Can they be the best partner? Maybe there is a break-in period. Moreover, ORCAD also has the original brother brother PCB tool ORCADLAYOUT. ALLEGO also has the original brother brother schematic design tool DesignEntryHDL. Some people even use ORCAD to draw schematics, and after generating netlists, they use PRETEL to draw PCBs. In order to take into account the habits of many people, CADENCE still integrates all tools (when PRETEL is not included) into an integrated environment. Users use whichever they want. For my part, I still think that ORCAD and ALLEGO can be the best partners. But now, whether it is our company or a lot of big companies, they use DesignEntryHDL and ALLEGO, maybe because they also have a special engineering manager, which is better connected with other simulation tools, and the interaction is also relatively Okay, maybe because they are close brothers ... But when I started to learn DesignEntryHDL, I felt that it really did nt meet my habit. Perhaps PROTEL's operating habits were preconceived, but DesignEntryCIS gave me a good feeling, although it was not very useful. Too. Fortunately, after learning DesignEntryHDL, I gradually got used to that operation.
Today, CADENCE collectively refers to these tools as the CadenceAllegro system interconnect design platform, which mainly includes: DesignEntryCIS (ORCAD) schematic design tools, DesignEntryHDL schematic design tools, AllegroPCBEditor printed circuit board design tools (ALLEGRO referred to above) ), AllegroAMSSimulator simulation tools, AllegroPCBSI signal integrity analysis tools, etc. It is worth mentioning that CADENCE does a better job of high-speed signal simulation. As we all know, as the signal frequency of circuit board cards is getting higher and higher, the size is getting smaller, etc. It works correctly. Therefore, signal integrity analysis becomes more and more necessary. CADENCE provides many such tools, such as the constraint manager in PCBEditor, etc., which can largely help users consider the integrity of the signal. About the version I use AllegroSPB15.2, but AllegroSPB16.x is already on the market.
Another point I want to mention is that Cadence not only provides the CadenceAllegro system interconnect design platform, but also IC design tools. I think that IC design will also be a required course for electronics engineers in the near future, just like doing PCB now. The board is very common, and I think it will also be common in the future. For example, there are companies such as SMIC in mainland China that can contract such projects, but for ordinary users, it may take a period of time. Coupled with the improvement of the situation in Taiwan, the chip manufacturing industry can be more optimistic, so it is necessary to master so one or two chip design software. I think.

PADS / PowerPCB

Although PADSPower appeared relatively late ^[4] , it has not been understood by the majority of users, but because it not only continues PADS's "powerful and easy operation" characteristics, but also has great improvements, it may be widely used in electronic circuits. Accepted by the designer. It may be because it is closely related to PCB board manufacturing. It started from PowerPCB5.0 and gradually gained popularity. Therefore, many people know about PowerPCB. Regarding the names of PADS and PowerPCB, I think it can be understood that the names of different versions are somewhat inconsistent. The original PADS series includes PowerLogic (schematic tools), PowerPCB (PCB tools), HyperLynx (signal analysis tools) and other major tools. The most recent versions of PADS2007, which are currently in use, include DxDesigner (project management), PADSLogic (schematic tools), PADSLayout (PCB tools), HyperLynx (signal analysis tools) and other major tools. So far, whether it is from schematic design, PCB design, high-speed signal analysis, or overall project management, PADS has indeed become a comprehensive and powerful EDA software.