I2S and digital signal path - in-line resistors?

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KlipschKid

Banned
Joined 2007
Hi,

The 384Khz dual ad1955 DAC arrived. I am pleasantly surprised ! The underside has decent ground planes. It isn't great quality but it is much better than the usual Taobao junk from mainland China. Depth and detail are impressive. I'll let it settle in for a few days and then start a thread about it.

An externally hosted image should be here but it was not working when we last tested it.
 
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duartejunior

Member
Joined 2011
marce said:
Its not going to have to high a data rate, so I would worry to much on that score. If the waves look OK (dont forget to take into account your scope probe loading) then I wouldn't worry.
Series resistors are there to match the signal to the layout topography, so there is realy no off the shelf value, it depend on the layout topography andf impedance, there are only two ways to determine the value:
Simulate the design using signal integrity tools and choose the best value, or try different values and see which gives the best measured result. Attached are some screen shots showing the actual difference different values of series resistors make, in this case 82R was chosen.
Vias and Kinks in traces will have no noticable effect on signal integrity at frequencies and rise time the DIYer is gonna be playing with, but with good layout you can minimise the number of layer changes a signal has between A & B.
My main concern would be a two layer board, these days ALL digital designs should be 4 layers min, with a full contigous ground plane. The main problem these days is signal rise time, which are forever getting faster and faster, and ultimetly it is the rise time of a signal (suignals) that determine whether a design is high speed.
Yes ground pour help if they are done correctly and are a must for two layer digital boards, but they need lots of stiching vias to be of any use.
Click to expand...

what software is this, this simulating the trace. thanks
 
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