I have a question for you.
Can you tell me in comment section what is reflection in single high speed net?
Hello people, welcome to stream PCB YouTube channel.
In this video we are going to talk about signal integrity.
For this topic I am referring to Signal Integrity Simplified book by Eric Bogatin.
I guess nothing else is required to understand this topic very better.
So if you wanted to go in very detail, you can click over the link given on the description and follow
this book.
Now before starting this topic, I want to thank EMA EDA for supporting steam PCB and providing all
the learning material which I will be sharing with the world through this YouTube channel so people
you can go to their website and get security CIS simulation tool free trial.
I'll put link in the description because very soon I am going to start simulation part further on this
high speed series.
People.
You can support this channel as well by enrolling into steam, PCB, mixed signal and high speed board
design courses.
With that said, let's move to our topic signal integrity.
Let's start with what is high speed signal.
So the signal which has clock frequency greater than or equal to 100MHz and rise time less than or equal
to one nanoseconds are high speed tracks or high speed signals.
Another question that we can ask what is what is signal integrity?
So signal integrity refers to all the problems arise due to interconnects in any high speed product.
That is what is signal integrity is all right.
So you can say all the problems due to.
Transmission line or interconnects.
In any high speed products.
All right.
So here we used another term.
Transmission line and interconnect.
So let's talk about that.
What are transmission line and interconnects to discuss further.
In transmission line let's suppose we have a transmitter.
All right.
Which kind of generate the signal.
And we have a receiver.
Right.
And between transmitter and receiver we have interconnects.
So when I'm using this term interconnects it refers to everything between transmitter and receiver.
For example it refers to package it referred to tracks in a board or PCB.
It referred to vias that we are using for layer change, and after layer change we are again routing
our tracks on a PCB.
Then again go back to package at the other side, or you can say at the receiver side, and then our
signal will finally receive.
So everything comes between transmitter and receiver is a part of interconnect.
All right.
And whenever interconnects are not properly designed either by the chip manufacturer or by the hardware
designer or PCB designer, then see problems arise.
All right.
So we will discuss that in very detail later.
Let's move to our another point.
So we can divide all type of C problems into three major categories.
So first category is noises, and under noises the C problem comes a a problem is ringing.
All right.
So how ringing looks.
So suppose we have a signal here.
And it just oscillate and then stabilize itself.
So if you are seeing this kind of waveform then this is related to ringing.
We will discuss cause and solution of these problems later.
Another problem can be ground bounce.
So this is our zero volt.
And instead of a constant zero volt on this you will see some spikes.
It can be positive negative or in both direction right.
So this is due to ground bounce.
Another problem can be reflection.
So how reflection waveform looks like.
It will be like something like this.
Right.
So here you can see first reflection here.
Second here like that.
Then another noises.
Problem is.
Near end crosstalk and far end crosstalk.
So here we can take an example how it looks like.
So this is our.
So ideally let's suppose this is our aggressor net.
All right.
So crosstalk means we have a aggressor net and we have a victim net.
So because of some signal is going to transfer on egress on it.
It is causing some spikes on victim minutes.
Right.
So if it is causing a positive spike on victim net then.
Due to this rising.
Okay, that will be our next or near end crosstalk.
And if it is causing negative spike then it will be fixed or far end crosstalk.
All right.
And this is our aggressor net.
Another problem can be.
Switching noise.
So here we have two waveforms.
This is again a kind of crosstalk Talk.
Right.
So one aggressor net it is switching but it is causing some problems in the victim net waveform.
Right.
This.
Right.
So this is kind of switching noise.
Another problem again comes under noises is load capacitance.
So how load how waveforms looks like for load capacitance case.
So it will be like this.
If you see any these kind of waveform it can be in positive and negative both direction.
Then this is happening due to load capacitance on the line.
All right.
Similarly we can move to another noise problems that can be due to attenuation okay.
So how waveforms looks like.
If there is attenuation in your track due to something.
All right.
We'll discuss that later.
So ideally the waveform should be like this right.
But due to attenuation it couldn't able to reach the full uh you can say uh the full voltage and start
slowing down.
Right.
So these are all the attenuated waveforms.
All right.
So these are some problems.
Similarly you can go for uh you can look for non monotonicity.
That is again a problem.
You can go for power bounds.
So similarly like ground bounce you will see spikes on power lines or power planes.
All right.
So these are all the noise problem.
Let's look for second category.
And second category is EMI and EMC.
Okay.
So I'm just going to tell you.
Definition here.
So EMI is most related to electromagnetic.
Emission from your hardware or chip or tracks.
Okay.
So that is emission from board or from PCB.
Or from product.
You can say anything right now.
EMC is related to compliance right.
So it is effect of emission to your board.
So that means your board is sitting somewhere inside a product.
And we have another part which is causing.
The electromagnetic emission.
Right.
And it is kind of affecting your PCB right.
So your PCB should be protected for both of the cases for emission, for electromagnetic interference
and for electromagnetic It's all right for both of the cases.
Your PCB should be designed like that.
All right.
Let's discuss the third category, which is related to timing.
Okay.
So timing is basically we are talking about clock period.
Okay.
So we have one clock period.
All right.
And we basically allocate that clock period to let's suppose 5 to 10 processes okay.
And due to signal integrity if the if something happened to this timing or this clock period okay.
Either it can be delay.
It can be attenuation.
It can be anything okay.
So it will cause interrupts.
Or you can say halt in these processes right.
Or stop these processes.
Right.
So these are all the problems which comes under.
Under the timing related signal integrity issues.
Okay.
We'll discuss that in more detail later.
If we'll explore more under these three categories, we'll get to know about 25 different problems.
Even more than that different signal integrity problems.
All right.
So we have to understand the root cause of these problems.
And what are the solutions okay.
Another step is now we can further devise divide these 25 or more than that problems into six major
parts that we are going to cover in upcoming videos.
So I hope this video was useful for you and you have learned couple of things.
In case of any doubt, or you have any questions you can put in the comment section, I will reply you
there ASAP.
Thank you.
See you on the next video.