So I want to have a oscilator driving a buffer/fanout IC to drive the SMB connections out to other components. 24.576MHz so not GHz but the design sheet recommends a trace designed for 50ohm impedance.
Do i simply layout and then adjust the thickness of the trace based on a calculation to adjust the trace width based on weight, thickness and length?
The only other way is to connect with a resistor in the way rather than trace (tune the wave guide?).
Do i simply layout and then adjust the thickness of the trace based on a calculation to adjust the trace width based on weight, thickness and length?
The only other way is to connect with a resistor in the way rather than trace (tune the wave guide?).
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The trace impedance depends on the width and the layer thickness, and the fiberglass dielectric. Trace impedance is never far from 50 Ohms, just like cable impedance. You need some kind of termination and series termination is the most efficient, ie a build-out resistor at the source. This assumes a single destination. Bussing a clock is very old fashion and a recipe for bad results. Modern electronics use clock chips with an output for every customer, so that every clock trace has only one reflection and the signal in the middle has a half step between signal going out and coming back. Professionals calculate the trace thickness and then ask the PCB vendor to make a set of samples because the PCB materials vary.
https://www.intel.com/content/www/u...uideline-use-series-termination-resistor.html
https://www.intel.com/content/www/u...uideline-use-series-termination-resistor.html
The osc would only see a single reflection /device at 50ohm. The clock distribution IC then splits and buffers to multiple outputs. There is only one clock consimer on each IC output. That way there should be a single reflection. The final consuming boards then terminate with 50R close to the clocked chip.