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Circuit Design

Scope and Description

This topic covers reliable electrical circuit design for spaceflight. Satellite electronics are exposed to the harsh environment of space, which imposes unique challenges for reliable circuit design. These challenges include parameter variations, extreme temperatures, aging, radiation effects, and edge case error modes. All of these factors must be considered when designing systems which - in many cases - will operate uninterrupted for years.

Resources under this topic are primarily software tools for electrical schematic capture and guidance regarding grounding, radiation effects mitigation, fault tolerance, high voltage, and other elements of circuit design for space flight.

Best Practices and Lessons Learned

  • Conducting preliminary circuit analyses in lockstep with circuit design is a great way to minimize design iterations and detect key risk areas prior to detailed circuit implementation.
  • Pay close attention to grounding schemes. Grounding issues in a spacecraft or its ground support equipment are often times the cause of test failures. Several guides under this topic address grounding.
  • Similar to circuit analysis, part selection should be conducted in parallel with the design process. The constraints imposed by the space environment often drive part selection which in turn can greatly reduce the circuit design trade space.
  • It is easy for schematics to become incomprehensible to outside reviewers as a design grows. To improve readability, break circuits into blocks which fit neatly on a single sheet and require minimal wire crossings. It is also advantageous for the flow of logic, electricity, etc. to be from left to right and top to bottom.

Resources

Software Tool
NASA

This interactive online software tool offers a step-by-step guide for determining radiation risks that ... apply given a set of simple input from the user. Smallsat teams can develop dose depth curves and single event effects (SEE) plots based on the orbit and other input parameters. In addition, R-GENTIC provides advice on electronics and software/firmware design for radiation tolerance in the specified environment.

Software Tool
KiCad

This free, open-source electronic design automation (EDA) suite can be used for schematic capture, printed ... circuit board (PCB) layout, and 3D modeling of the completed PCB. This suite includes add-on design tools for developing engineering drawings, calculating various component metrics, and plugins for integration with third-party tools.

Software Tool
Altium

Altium Designer is a software tool that encompasses the entire PCB development process - from schematic ... capture to assembly. Altium is a powerful tool that is appropriate for complex designs and includes features comparable to Cadence's offerings (OrCAD and Allegro) for electronics design.

Software Tool
Autodesk

Autodesk Eagle is a software tool for performing electronic design and layout. Refer to their website ... for more information or a free download for hobbyists.

This design guide is intended to provide information and mitigation techniques regarding hazards presented ... by connecting and disconnecting electrical connectors on spacecraft. Deadfacing is the "removal of power from a circuit prior to de-mating/mating a circuit interface." This guide covers existing NASA requirements (circa 2002) and reasons for deadfacing.

White Paper
Christian Poivey et al.

These slides describe the harsh radiation environment in space and the technical challenges it poses. ... It also presents a variety of design techniques for mitigating and planning for these challenges. The slides present useful graphics for understanding the impact of these radiation effects on electrical design.

White Paper
NASA

Several common types of space instruments require high voltage power. High voltage failures are commonly ... caused by marginal electronic design and electrical insulation problems. This design guide provides valuable advice for the purpose of avoiding these potentially mission-compromising high voltage failures.

White Paper
Analog Devices

This is a multi-part article discussing exactly what the title states. It covers the harsh space environment ... and the challenges it poses to electronics designers. It also discusses technological trends and Analog Devices' efforts within this area.

Article
electronic-circuit-design-and-analysis-for-space-a

This article encompasses a variety of content pertaining to electrical design and the space radiation ... environment. SEE, TID, and ELDRS are discussed in moderate detail before two design examples are given. These examples demonstrate design approaches for handling these radiation effects.

Good spacecraft electrical grounding is an integral part of mission success. This handbook describes ... system level spacecraft grounding architecture options options, with the objective of reducing electromagnetic interference and unwanted electrical interaction between components and/or subsystems.

Complex electronics are "programmable and designable complex integrated circuits." Examples of these ... include, but are not limited to, FPGAs, CPLDs, ASICs, and SoCs. This handbook provides an overview of FPGA, CPLD, ASIC, and SoC devices, how they are designed and programmed, and assurance and verification activities for them. It also covers trends in design and assurance for these complex devices. This document is coming from a traditional, high-reliability perspective, but the intended audience and "overview" level of detail makes this a good introduction these design, assurance, and verification tasks. Section 3 provides a useful glossary of terms.

Article
EDN.com

This is a well-written article detailing some of the important trends in space electronics and more the ... space industry as a whole. It is a good introductory article and appropriate for both technical and non-technical readers.

Software Tool
Cadence Design Systems

OrCAD Capture is a suite of PCB schematic design tools. It can be used with another Cadence software ... tool, Allegro PCB Designer, for circuit board layout. OrCAD Capture is a powerful tool that is appropriate for complex design tasks.

This NASA lesson briefly describes best practices and guidelines for designing and manufacturing space ... flight power supplies to improve reliability and reduce component failures. Special attention is given to corona discharge.

Software Tool
LibrePCB

This is a free, open source software tool for schematic capture and board layout. Compared to other free ... tools, LibrePCB focuses on easy component library management and version control. However, it is less powerful and therefore not as appropriate for complicated designs.

This NASA standard provides detailed information on requirements and recommendations for the design and ... development of high-reliability printed circuit boards (PCBs). Various certifications for PCB designers and visual inspectors are provided as well as additional resources for PCB standards and examples.

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