Printed Circuit Design & Fab - February 2009 - (Page 39)

LAYOUT toolS FiGurE 1. The inclusion of sophisticated interactive routing features within PCB layout environments calls into question the need for stand-alone autorouting applications. FiGurE 2. The swappable nature of pin assignments on programmable devices such as FPGAs presents some unique opportunities for designers. Supporting this with automation, requires the convergence of multiple design disciplines and a unification of the different design tools involved. must now be viewed in a wider electrical and physical context to preserve signal integrity. This is driven by both the increasing switching and clock speeds of the circuitry itself and new fabrication technologies such as microvias and high density interconnect boards. The wider use of large-scale programmable devices in designs also introduces complexities because of the multiple programmable I/O standards available at the pins of these devices, as well as the fluid nature of the signal-to-pin assignments that is the hallmark of these devices (FiGurE 2). What this all means is that board routing is taking on new and complex dimensions, with a much higher level of interdependency on factors that have traditionally not had to be considered when choosing routing paths. Assessing this intricate interplay of issues is something that humans – engineers at least – are well suited to. The challenge has been to reduce the potential interplay into a tight and formalized set of constraints so that a computer can effectively handle the tradeoffs automatically. Computers are great at running complex path finding algorithms. Designers are great at analyzing the myriad factors that go into choosing a desired path. The best ‘bang for buck’ in terms of automating the routing process is to combine the strengths of the designer with that of the computer and support the board designer with automation features that assist, rather that take over, the manual routing process. And it is this area of interactive routing that has been the focus of some of the most productive developments in design tools in the last decade. Features such as intelligent route auto-completion, impedance-controlled routing, the ability to route buses and differential pairs in a single action and guided autorouting (where the designer chooses the approximate path and the router engine does the grunt work of actually laying the traces to comply with the design rules) have FEBRUARY 2009 enabled designers to cope with the increasing complexity of modern boards without getting bogged down in the minutiae of autorouter set up. There’s no doubt that better automation of the routing process can save time and increase quality in board design. But the complexity of the constraints surrounding board design today would suggest that integrating autorouting functionality directly into the board design and layout environment and giving designers interactive control over the automation is the best way to deliver productivity gains. It reduces the need to define common constraints in two separate applications, reduces the dangers and time wasted in transferring design data between applications and harnesses a designer’s superior ability to weigh up complex priorities across different design domains. While standalone autorouters can still be an important part of a board designer’s toolkit in the short term, increasingly, the real value of automation in electronics design lies in facilitating the convergence of the various disciplines that go into creating an electronic product. To do this, the design tools themselves need to converge in order to provide a single model of the overall design. This unified approach is necessary if we are to cope with the increasing complexity inherent in the next generation of electronic products. So, do you really want a better autorouter? The answer is still yes! But that autorouter will probably be delivered as the interactive routing features of your nextgeneration electronics design system. pCd&f roB irwin is product marketing manager for Altium and can be reached at rob.Irwin@altium.com. printEd CirCuit dESign & fAB 39

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - February 2009

Printed Circuit Design & Fab - February 2009 Contents Our Line Market Watch Around the World Happenings ROI Tip Jar BGA Bulletin Interconnect Strategies Final Finsh Forum Defects Database Embedded Active Components In Multilayer LCP Packages Simulation: The Need for Speed Advanced Registration Systems The DC Design Squeeze Ad Index Do You Really Want a Better Autorouter? Designing With Conductive Materials, Part 1 Off th eShelf Marketplace On the Forefront

Printed Circuit Design & Fab - February 2009

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