Right Angle Trace Question

[rhnrgn]

Hello,

I know that right angle traces are bad esspecially in switching lanes.

I have a trace which will carry 100 MHz.

I want to ask you if a change the direction of trace with via, is this mean right angle?

There is a drawing which will help you to understand.

Best Regards

 

[marce]

Right angle traces do not cause any problems below GHz circuitry, so you basic information in incorrect, it is a myth. Every via a signal travels through means that signal is going through two right angles... so no problems.

 

[bert_kak]

Hello,

I know that right angle traces are bad esspecially in switching lanes.

I have a trace which will carry 100 MHz.

I want to ask you if a change the direction of trace with via, is this mean right angle?

There is a drawing which will help you to understand.

Best Regards

View attachment 122384

With high speed signals, we need to maintain the impedance of the line (characteristic impedance) to be of the same value throughout the line. This is needed to prevent signal reflection that causes signal distortion. If the line have 90 degree routing, it just means that there is an extra copper on the edge as shown in the image below thus it will induce extra capacitance which will alter your impedance in the portion of the right angle.


If you are adding a via, looking at the top layer alone, there will be changes in the copper area means that there will be extra capacitance thus changing the impedance. If the signal is passing thru the via, the via will be considered as an inductance thus changing the impedance again.

100MHz might still be safe but look at how fast the rise time to check if considering these things will affect your signal. If you can prevent having a via or 90 degree line, please to do so.

 

[rhnrgn]

With high speed signals, we need to maintain the impedance of the line (characteristic impedance) to be of the same value throughout the line. This is needed to prevent signal reflection that causes signal distortion. If the line have 90 degree routing, it just means that there is an extra copper on the edge as shown in the image below thus it will induce extra capacitance which will alter your impedance in the portion of the right angle.
View attachment 122869

If you are adding a via, looking at the top layer alone, there will be changes in the copper area means that there will be extra capacitance thus changing the impedance. If the signal is passing thru the via, the via will be considered as an inductance thus changing the impedance again.

100MHz might still be safe but look at how fast the rise time to check if considering these things will affect your signal. If you can prevent having a via or 90 degree line, please to do so.

This is the answer i was looking for. Best Regards

 

[marce]

With high speed signals, we need to maintain the impedance of the line (characteristic impedance) to be of the same value throughout the line. This is needed to prevent signal reflection that causes signal distortion. If the line have 90 degree routing, it just means that there is an extra copper on the edge as shown in the image below thus it will induce extra capacitance which will alter your impedance in the portion of the right angle.
View attachment 122869

If you are adding a via, looking at the top layer alone, there will be changes in the copper area means that there will be extra capacitance thus changing the impedance. If the signal is passing thru the via, the via will be considered as an inductance thus changing the impedance again.

100MHz might still be safe but look at how fast the rise time to check if considering these things will affect your signal. If you can prevent having a via or 90 degree line, please to do so.

It has NO EFFECT until you reach microwave speeds (GHzs) do some more research.

From the main man himself... there are newer comments from Dr Howard Jonson, that I will try and dig out.
http://www.sigcon.com/Pubs/edn/bigbadbend.htm

For fun....
http://www.ultracad.com/articles/flying.htm

- - - Updated - - -

Also draw out a signal going through a via as a section view then tell me how many 90 deg corners your signal has travelled through....