Schematic capture

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Eeschema open source schematic capture. Part of the KiCad suite Kicad Eeschema screenshot.jpg
Eeschema open source schematic capture. Part of the KiCad suite

Schematic capture or schematic entry is a step in the design cycle of electronic design automation (EDA) at which the electronic diagram, or electronic schematic of the designed electronic circuit is created by a designer. This is done interactively with the help of a schematic capture tool also known as schematic editor.

Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems such as integrated circuits and printed circuit boards. The tools work together in a design flow that chip designers use to design and analyze entire semiconductor chips. Since a modern semiconductor chip can have billions of components, EDA tools are essential for their design.

Circuit diagram graphical representation of an electrical circuit

A circuit diagram is a graphical representation of an electrical circuit. A pictorial circuit diagram uses simple images of components, while a schematic diagram shows the components and interconnections of the circuit using standardized symbolic representations. The presentation of the interconnections between circuit components in the schematic diagram does not necessarily correspond to the physical arrangements in the finished device.

Electronic circuit electrical circuit with active components such as transistors, valves and integrated circuits; electrical network that contains active electronic components, generally nonlinear and require complex design and analysis tools

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. To be referred to as electronic, rather than electrical, generally at least one active component must be present. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another.

Contents

The circuit design is the very first step of actual design of an electronic circuit. Typically sketches are drawn on paper, and then entered into a computer using a schematic editor. Therefore schematic entry is said to be a front-end operation of several others in the design flow.

The process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit. For simple circuits the design process can often be done by one person without needing a planned or structured design process, but for more complex designs, teams of designers following a systematic approach with intelligently guided computer simulation are becoming increasingly common. In integrated circuit design automation, the term "circuit design" often refers to the step of the design cycle which outputs the schematics of the integrated circuit. Typically this is the step between logic design and physical design.

In software engineering, the terms front end and back end refer to the separation of concerns between the presentation layer, and the data access layer of a piece of software, or the physical infrastructure or hardware. In the client–server model, the client is usually considered the front end and the server is usually considered the back end, even when some presentation work is actually done on the server itself.

Design flows are the explicit combination of electronic design automation tools to accomplish the design of an integrated circuit. Moore's law has driven the entire IC implementation RTL to GDSII design flows from one which uses primarily stand-alone synthesis, placement, and routing algorithms to an integrated construction and analysis flows for design closure. The challenges of rising interconnect delay led to a new way of thinking about and integrating design closure tools.

Despite the complexity of modern components – huge ball grid arrays and tiny passive components – schematic capture is easier today than it has been for many years. CAD software is easier to use and is available in full-featured expensive packages, very capable mid-range packages that sometimes have free versions and completely free versions that are either open source or directly linked to a printed circuit board fabrication company.

Ball grid array

A ball grid array (BGA) is a type of surface-mount packaging used for integrated circuits. BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be put on a dual in-line or flat package. The whole bottom surface of the device can be used, instead of just the perimeter. The traces connecting the package's leads to the wires or balls which connect the die to package are also on average shorter than with a perimeter-only type, leading to better performance at high speeds.

Computer-aided design constructing a product by means of computer

Computer-aided design (CAD) is the use of computers to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing. CAD output is often in the form of electronic files for print, machining, or other manufacturing operations. The term CADD is also used.

Open-source software software licensed to ensure source code usage rights

Open-source software (OSS) is a type of computer software in which source code is released under a license in which the copyright holder grants users the rights to study, change, and distribute the software to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. According to scientists who have studied it, open-source software is a prominent example of open collaboration. The term is often written without a hyphen as "open source software".

In past years, schematic diagrams with mostly discrete components were fairly readable. However, with the newer high pin-count parts and with the almost universal use of standard letter or A4 sized paper, schematics have become less so. Many times, there will be a single large part on a page with nothing but pin reference keys to connect it to other pages.

Readability levels can be enhanced by using buses and superbuses, related pins can be connected into a common bus and routed to other pages. Buses don't need to be just the traditional address or data bus directly linked pins. A bus grouping can also be used for related uses, such as all analog input or all communications related pin functions.

Readability is the ease with which a reader can understand a written text. In natural language, the readability of text depends on its content and its presentation. Researchers have used various factors to measure readability, such as

Other considerations

After the circuit design is captured in a schematic, most EDA tools allow the design to be simulated.

Schematic capture involves not only entering the circuits into the CAD system, but also generally calls for decisions that may seem more appropriate for later in the design, such as package choice. Although you may be able to change the package later, many PCB CAD systems ask you to choose both the part and package when placing it into the schematic capture program.

This also brings into play such considerations as prototyping and assembly. In a high-volume assembly environment, there will be plenty of opportunities for DFM analysis. However, in a rapid prototyping environment such as at assembly houses specializing in low-volume/high-mix and quick turnaround times, the pick and place machines are programmed directly from the board layout files. Careful package selection during schematic capture will save time during the assembly and debug process.

With new parts, the CAD system may not have your chosen component in its parts library, so you may need to create the parts library yourself. Again, you may at the time not be overly concerned with the package, but careful creation of the part library will save time and risk later.

After the circuit design is captured in a schematic, then the PCB layout can begin.

See also

Further reading

Related Research Articles

A schematic, or schematic diagram, is a representation of the elements of a system using abstract, graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to the key information the schematic is intended to convey, and may include oversimplified elements in order to make this essential meaning easier to grasp. For example, a subway map intended for passengers may represent a subway station with a dot. The dot is not intended to resemble the actual station at all; instead, it aims to give the viewer information without unnecessary visual clutter. A schematic diagram of a chemical process uses symbols in place of detailed representations of the vessels, piping, valves, pumps, and other equipment that compose the system; in so doing, it emphasizes the functions of these individual elements--and the interconnections among them--and suppresses their particular physical details. In an electronic circuit diagram, the layout of the symbols may not look anything like the circuit as it appears in the physical world: instead of representing the way the circuit looks, the schematic aims to capture, on a more general level, the way it works.

EAGLE (program) program

EAGLE is a scriptable electronic design automation (EDA) application with schematic capture, printed circuit board (PCB) layout, auto-router and computer-aided manufacturing (CAM) features. EAGLE stands for Easily Applicable Graphical Layout Editor and is developed by CadSoft Computer GmbH. The company was acquired by Autodesk Inc. in 2016.

CADSTAR

CADSTAR is a Windows-based electronic design automation (EDA) software tool for designing and creating schematic diagrams and printed circuit boards (PCBs). It provides engineers with a tool for designing simple or complex, multilayer PCBs. CADSTAR spans schematic capture, variant management, placement, automatic and high-speed routing, signal integrity, power integrity, EMC analysis, design rule checks and production of manufacturing data.

TARGET (CAD software)

TARGET 3001! is a CAD computer program for EDA and PCB design, developed by Ing.-Büro Friedrich in Germany. It supports the design of electronic schematics, PCBs, and device front panels. It runs under Windows and is available in English, German and French.

OrCAD electronic design automation software

OrCAD Systems Corporation was a software company that made OrCAD, a proprietary software tool suite used primarily for electronic design automation (EDA). The software is used mainly by electronic design engineers and electronic technicians to create electronic schematics and electronic prints for manufacturing printed circuit boards. OrCAD was taken over by Cadence Design Systems in 1999 and was integrated with Cadence Allegro since 2005.

XCircuit

XCircuit is a Unix/X11 and Windows program for drawing publication-quality electrical circuit schematic diagrams and related figures and the production of circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical and writes both PostScript output and hierarchical SPICE netlists. Circuit components are saved in and retrieved from libraries which are fully editable. XCircuit does not separate artistic expression from circuit drawing; it maintains flexibility in style without compromising the power of schematic capture.

gEDA electronic design automation software

The term gEDA refers to two things:

  1. A set of software applications used for electronic design released under the GPL. As such, gEDA is an ECAD or EDA application suite. gEDA is mostly oriented towards printed circuit board design. The gEDA applications are often referred to collectively as "the gEDA Suite".
  2. The collaboration of free software/open-source developers who work to develop and maintain the gEDA toolkit. The developers communicate via gEDA mailing lists, and have participated in the annual "Google Summer of Code" event as a single project. This collaboration is often referred to as "the gEDA Project".
NI Multisim electronic schematic capture and simulation program

NI Multisim is an electronic schematic capture and simulation program which is part of a suite of circuit design programs, along with NI Ultiboard. Multisim is one of the few circuit design programs to employ the original Berkeley SPICE based software simulation. Multisim was originally created by a company named Electronics Workbench, which is now a division of National Instruments. Multisim includes microcontroller simulation, as well as integrated import and export features to the Printed Circuit Board layout software in the suite, NI Ultiboard.

KiCad free software suite for electronic design automation (EDA)

KiCad is a free software suite for electronic design automation (EDA). It facilitates the design of schematics for electronic circuits and their conversion to PCB designs. KiCad was originally developed by Jean-Pierre Charras. It features an integrated environment for schematic capture and PCB layout design. Tools exist within the package to create a bill of materials, artwork, Gerber files, and 3D views of the PCB and its components.

Altium Limited is an American, Australian-domiciled owned public software company that provides PC-based electronics design software for engineers who design printed circuit boards. Founded as Protel Systems Pty Ltd in Tasmania, Australia in 1985, Altium now has regional headquarters in the United States, Australia, China, Europe, and Japan, with resellers in all other major markets.

Altium Designer electronic design automation software

Altium Designer is a PCB and electronic design automation software package for printed circuit boards. It is developed by Australian software company Altium Limited.

PCB (software) free and open-source software suite for electronic design automation

PCB is a free and open-source software suite for electronic design automation (EDA) - for printed circuit boards (PCB) layout. It uses GTK+ for its GUI widgets.

DesignSpark PCB

DesignSpark PCB is a free electronics design software, Although there is no charge for the software, the user must register with the website to unlock the program and it displays advertisements which must be acknowledged before the user can begin working.

DipTrace

DipTrace is an EDA/CAD software for creating schematic diagrams and printed circuit boards. The developers provide a multi-lingual interface and tutorials. DipTrace has 4 modules: schematic capture editor, PCB layout editor with built-in shape-based autorouter and 3D-preview & export, component editor, and pattern editor.

Pulsonix Software für Schaltplan Erstellung und Leiterplatten Design

Pulsonix is an electronic design automation (EDA) software suite for schematic capture and PCB design. It is produced by WestDev, which is headquartered in Gloucestershire, England, with additional sales and distribution offices overseas. It was first released in 2001, and runs on Windows.

Upverter

Upverter is an EDA system delivered in a web-browser which enables hardware engineers to design, share, and review schematics and printed circuit boards. It additionally features the ability to generate a bill of materials, Gerber files, and a 3D rendering. Upverter provides web-based tools for editing schematic diagrams and for laying out printed-circuit boards. It does not require payment for open-source projects.

CircuitMaker is electronic design automation software for printed circuit board designs targeted at the hobby, hacker, and maker community. CircuitMaker is available as freeware, and the hardware designed with it may be used for commercial and non-commercial purposes without limitations. It is currently available publicly as version 1.3 by Altium Limited, with the first non-beta release on January 17, 2016.

EasyEDA is a web-based EDA tool suite that enables hardware engineers to design, simulate, share - publicly and privately - and discuss schematics, simulations and printed circuit boards. Other features include the creation of a Bill of Materials, Gerber and pick and place files and documentary outputs in PDF, PNG and SVG formats.

Proteus Design Suite electronic design automation software

The Proteus Design Suite is a proprietary software tool suite used primarily for electronic design automation. The software is used mainly by electronic design engineers and technicians to create schematics and electronic prints for manufacturing printed circuit boards.