Column: Embedded design
A relaxed approach to PCB design
By Myk Dormer, RF Engineer and Director, Smallwireless Limited P
CBs are everywhere; there is barely an electronic system that doesn’t contain one or more of them. As important as the
PCB itself is, its design is what we will discuss here and, more specifi cally, how to improve it. Converting a theoretical schematic
circuit or a handmade “mess of wires” prototype into a viable, fully-functional circuit board design (or “artwork”) is skilled work, even with tools and computerised assistance. Larger organisations use highly-specialised PCB designers, and even entire departments. In an ideal world, an engineer would
work closely with a PCB designer to bring a new product into life. However, many smaller companies rarely have the same resources, leaving the PCB design task to the engineers themselves – which is not necessarily a bad thing. Especially in RF circuits or fast digital
designs, the actual geometry of the conductors on the board and the location of components relative to others can exert a powerful infl uence on the circuit behaviour. In high-power designs it is the thermal characteristics of the board
that are important, while in the extreme case of certain microwave designs, the copper tracks and patterns actually are the “components” themselves. Having an engineer at least rough out
the initial PCB designs makes a lot of sense, aided by PCB design soſt ware, or a “CAD package”. T e problem here is that, while it
is quite possible to become tolerably profi cient in PCB layout, it is very unlikely that the acquired skill level is of a professional PCB designer. With that in mind, here are a few warnings and suggestions that will prove helpful:
• Use the right tool T ere are hundreds of diff erent CAD packages in the market, ranging from immense, complex systems that integrate every aspect of the design process, to simple freeware apps that are a little more than sketching tools. Choose a tool that suits you within your budget. You will be spending a lot of hours staring at it, so if it has features that irk you at the start then you will be screaming at it by the end. As a bare minimum you need a package that combines schematic capture with board layout (with proper interconnection between them), with fl exible part libraries
that allow you to generate new parts, and which generates reliable Gerber format output fi les for board production.
• Size is everything It is exponentially harder to package a circuit into a tiny space on the PCB, compared to laying out the same parts into a more relaxed, larger area. T is sounds obvious, but I have seen many resources wasted on pushing for the smallest possible size, when a modest increase in PCB size would turn a massive headache into a ten-minute job. Considering the effort of designing
complex multi-layer boards, and the likelihood of interference between circuit elements, it’s worth separating the various parts of the circuit onto multiple simpler boards, and stacking them into a 3D assembly. This is particularly valuable when implementing low-noise RF VCO circuits, where susceptibility to pick up and ground currents can be problematic, and where layers of local screening are necessary.
• Challenge dogma When PCB design rules and restrictions get discussed, look very closely at exactly what is being stipulated. I have
In high power designs it is the thermal characteristics of the board that are important, while in the extreme case of certain microwave designs, the copper tracks and patterns actually are the “components” themselves
14 November 2026
www.electronicsworld.co.uk
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