Author Topic: How to do logic level compatibility for differential signals?  (Read 1258 times)

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Offline electrowhizTopic starter

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Hi All,

When we do logic level compatibility or noise margin analysis for single ended signals we will check the below criteria:
Voh > Vih
Vol< Vil

How we should do the logic level compatibility for differential signals?

Thanks
 

Offline Aggressive_Doughnut

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Re: How to do logic level compatibility for differential signals?
« Reply #1 on: April 03, 2019, 04:23:57 pm »
Most datasheets contain the information you are looking for: example.  Generally, you are measuring the difference (V_ID which I always assumed means Input Difference Voltage) and determining if that difference surpasses a certain threshold.
 

Online tggzzz

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Re: How to do logic level compatibility for differential signals?
« Reply #2 on: April 03, 2019, 04:49:26 pm »
Common mode voltages should be compatible, i.e. mean output voltage within mean input voltage range specified by the reciever.
Differential mode voltage should be compatible.
If necessary, the max and min voltages should be compatible, but that is often implicit in the common and differential mode voltage specifications.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline electrowhizTopic starter

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Re: How to do logic level compatibility for differential signals?
« Reply #3 on: April 04, 2019, 01:26:47 pm »
Thanks for the reply. I also have another doubt. What is the difference between AC logic level and DC logic level?
 

Online tggzzz

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Re: How to do logic level compatibility for differential signals?
« Reply #4 on: April 04, 2019, 01:37:01 pm »
Thanks for the reply. I also have another doubt. What is the difference between AC logic level and DC logic level?

I don't recognise those terms. I could guess, but that would be a waste of everybodies time.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 


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