Controlled Impedance

All types available single ended and differential.

Surface microstrip
Offset stripline
Symmetrical stripline
Embedded microstrip
Coated microstrip
Differential pairs
Design support

All impedance values,
28, 50, 75, 100

Impedance tolerance
Normal 10%
Advanced 5%
Specials 3%

To achieve the best results first time, please contact Wendy Davis in our engineering department who will help with your calculations and builds. We can engineer the design to allow for the manufacturing process E.G. The dielectric constant after bonding.

We have a polar CITS 500 S4 T.D.R tester and polar CITS 25 version 1,0,0,3 calculator.

Test results can be supplied to verify your product.

In many designs today the impedance characteristics of tracks need to be considered at the engineering stage. The formulas for impedance are very complex and specialist software is used to calculate results.

At Wrekin however, we also understand that these calculations are approximate especially when used for dual stripline and buried microstrip. We understand the importance of the relative dialectric constant which will vary between manufacturers and over years of experience we have built up an enviable reputation for being able to calculate and hold very demanding tolerances.

There are certain design criteria that should be considered. For example, where there is a branch in tracks this can lead to a mismatch of up to 50%. One way of improving this is to ensure that the branch is within a distance from the gate equal to the rise time of the signal.

In critical situations, we can adjust the tracks to match at the branch.
This is done by changing the track width to ensure that the impedance requirements are matched.

Mostly we can assume that the impedance of a track is defined by its relationship to a power plane. However, there are occasions when we need to be wary. One is when dealing with very high rise times where the inductance of the planes comes into play and another is where we take the reference from one plane to another such as when a signal is moved through a via to another layer.