pcb-rnd knowledge pool


High frequency boards

Ihighfreq by Tibor 'Igor2' Palinkas on 2020-06-07

Tags: index, high, frequency, microwave, radio, signal, integrity

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Abstract: This index node collects references to other pool nodes giving an overview on what tools and techniques pcb-rnd offers to help the design of high frequency boards.


The tree classes

pcb-rnd offers three classes of tools:

It is possible to design a high frequency board without using any of these, but using these features can speed up the design process and can help making sure the resulting board fulfills all high frequency related requirements.

1. Board editing aids

1.1. Set up the layer stack properly

Layer groups have attributes . Make sure you have set at least thickness on all copper and substrate layer groups and dielectric on all substrate groups. Easiest way to do this manually:

1.2. Set up the routing style

Most high speed or high frequency boards will have transmission lines which will require to follow an exact geometry (trace width and clearance). The easiest way to do this is using routing styles:

1.3. Transmission line calculator + autosetup

It is possible to get pcb-rnd do both of the above semi-automatically, using a calculator dialog box, using the imp_setup user script from edakrill . The advantages are that it makes it much easier and faster to set up layer group and routing style properties, plus there's no room for copy&paste error while manually coping data. It can also be used to look at current settings and calculate approximate impedances.

1.4. via fencing

Some transmission lines require via fencing: post-wall waveguides, laminated waveguides. There's an extended object for making it very easy to draw and maintain line-of-via objects , removing the step of manually creating and moving each via.

2. Design rule checker

The following DRC scripts can help checking high speed designs:

3. Simulation

It is possible to use OpenEMS to simulate parts of the board. TODO: figure how this can be used for transmission lines.