Why is the trace right angle?

[ZTZ]

Hello,
I get the demo board of TI's TPA0212.
I find the trace right angle,i don't the reason.
Help.
Regards,
Fourier

 

[creepy]

It could be caused by an autorouter...

 

[House_Cat]

There is no reason not to use right angles. This is an audio board, and right angle traces have absolutely no effect on signal quality.

If you have been taught that right angle traces are always bad - you have been taught incorrectly. In fact, when necessary, right angle traces can be used on controlled impedance RF boards with NO measurable effect on signal quality or EMI. There have been several experiments and analytical papers written in the past few years that disprove the myth that right angles cause impedance mismatch, radiation, etc, on high speed boards.

The myth of right angle PCB traces is one of those 'Rules of Thumb' that keeps getting passed along without question or proof. Mathematically, there is a small change in trace capacitance at a corner - in real world PCB measurements, the effect of the capacitance and vanishingly small fringing (evanescent) fields is orders of magnitude smaller than other effects such as variations in dissipation constant, uneven copper etch, trace surface roughness, and impedance changes at component leads.

 

[ZTZ]

Ths.
I'm interested in "several experiments and analytical papers written in the past few years that disprove the myth that right angles cause impedance mismatch, radiation, etc, on high speed boards. "
But idon't search the papers.Who can give these literatures?
THS
Regards.
fourier

 

[House_Cat]

I'm interested in "several experiments and analytical papers written in the past few years that disprove the myth that right angles cause impedance mismatch, radiation, etc, on high speed boards. "
But idon't search the papers.Who can give these literatures?

Here are a few references to get you started:

**broken link removed**

An independent experiment related to the above is at:

https://www.ultracad.com/articles/90deg.pdf


Text References:

High Speed Signal Propagation by Howard Johnson and Martin Graham, pp304-305

High Speed PCB Design by Lee W. Ritchey and James C. Blankenhorn, pp106-107

High Speed Digital System Design by Stephen H. Hall, Garrett W. Hall, and James A. McCall, pp97-99