what is high speed PCB design?

[sapphire_2010]

HI all,
is there any true definition for High speed PCB design? any frequency range or it depends on edge rate/rise time as well.
Customer has assigned one project having clock frequency 10MHz-20MHz . should i need to treat this as a high speed signal & do the PCB Layout as per highspeed PCB design requirements?
Any help would be appreciated
thanks

 

[cameo_2007]

i dont think that 20MHz has to be considered as high speed design. However, taking consideration of high speed PCB layout is not a bad idea.

 

[emamss]

the important point that move us to High speed PCB Zone is the rise time of the Signal not the Frequency.

 

[psatish1264]

Hi,
No need consider that design as high speed design.

 

[emamss]

the design be High speed or we consider trace on PCB as transmission line When

speed of signal in the PCB(inch/second)*time to signal travel from source to destination(second) = safety factor * trace length on PCB(inch)

where speed of the signal in PCB = C/Sqrt(Er)
Safety Factor from 4 ~ 10

this mean some time frequency be 50Hz mean wave length of this signal 6KK
case one in power line the length of the transmission line be thousands of kilometer therefore we consider it as transmission line
case two inside the Home where the length of cable be in maximum 1K therefore we don't consider it transmission line and we can connect the electricity with random and no need to matching inside the home

therefore the new device be small in size to be away smaller than critical length

 

[marce]

High speed it determined by the signal rise time, look up Dr Howard Johnson, or search this forum for similar discussion on this matter.

 

[emamss]

determined by two factor Rise time and length of the trace in the PCB