Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

high speed signals in PCB

senmeis

Advanced Member level 4
Joined
Nov 26, 2014
Messages
103
Helped
0
Reputation
0
Reaction score
0
Trophy points
16
Activity points
741
Hi,

is it correct that high speed signals propagate in PCB as waves in dielectric materials such as FR4 according to microstrip principle?

Senmeis
 

stenzer

Full Member level 5
Joined
Oct 1, 2012
Messages
300
Helped
53
Reputation
106
Reaction score
52
Trophy points
1,308
Activity points
3,777
Hi,

it basically depends on your frequencies as well as on the length of your traces.
As a rule of thumb, if the trace length is shorter than a tenth of the wavelengt of the highest frequencies (\[{l}_{trace,max}\] < \[\frac{{\lambda}_{max}}{10}\]), wave propagation effects are negligible.

BR
 

volker@muehlhaus

Advanced Member level 5
Joined
Apr 11, 2014
Messages
2,498
Helped
981
Reputation
1,964
Reaction score
962
Trophy points
113
Activity points
14,810
For time domain guys, we need to care about controlled impedance when the line propagation delay becomes significant compared to pulse rise/fall time.
 

wwfeldman

Advanced Member level 3
Joined
Jan 25, 2019
Messages
735
Helped
174
Reputation
348
Reaction score
179
Trophy points
43
Activity points
5,343
@stenzer
does the measure of 1/10 wavelength mean only 1/10 wavelength or does it mean integer number of wavelengths + 1/10 wavelength?
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
47,277
Helped
13,995
Reputation
28,243
Reaction score
12,645
Trophy points
1,393
Location
Bochum, Germany
Activity points
275,228
is it correct that high speed signals propagate in PCB as waves in dielectric materials such as FR4 according to microstrip principle?
The PCB structures have to be analysed as planar transmission lines, line type according to the geometry e.g. micro strip, embedded stripline, coplanar strips with or w/o ground, coplanar waveguide.
 

stenzer

Full Member level 5
Joined
Oct 1, 2012
Messages
300
Helped
53
Reputation
106
Reaction score
52
Trophy points
1,308
Activity points
3,777
@wwfeldman
It means smaller than a tenth. So if the length of your trace is shorter than \[\frac{\lambda}{ 10}\] (e.g. \[{l}_{trace,max}\] = \[\frac{\lambda}{12.3456789}\]) wave propagation effects can be neglected, see The RF and Microwave Handbook.

BR
 

Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top