Generating Eye Diagram In ANSYS AEDT Using the HFSS 3D Layout & Circuit Tools Based on SIwave Solver

Hello, this is Ibrahim Nassar with Ozen Engineering. In this demo, we will be simulating a serial channel on a PCB design using the SIwave Solver within the Ansys HFSS 3D layout tool in Ansys Electronic Desktop.

Then we will link that HFSS 3D layout tool design into a circuit and generate an eye diagram using the Ansys transient solver. In another demo, we showed how we can directly add a transient simulation within the HFSS layout without the need to add a circuit.

But here in this flow, we will add a circuit as adding the circuit can make the approach more suitable for other design workflows. Here is the workflow of this approach. We basically start by importing a PCB board file or opening a project that already has it.

We set up the simulation in an HFSS layout tool. Then we add the Ansys SIwave solver and we run the Ansys SIwave analysis. After that, we link the HFSS 3D layout tool into a circuit, then we set up the transient circuit simulation, and then we analyze and create eye diagrams.

So, here's the file that we will start with. This is a complex file, however we will be simulating the transmission lines that connect the controller to the connector. We already have the ports created here.

If we right click on a port and select Zoom To, here is one of the ports, here is the second port. We are basically putting ports at the end of the disconnector side and other ports are here on the other side inside the controller. So here we set up an Ansys SIwave solution.

You can do that by right-clicking on Analysis and Add SIwave Solution Setup and we select the first option. Here the analysis is defined, we are using a balanced signal integrity simulation, balanced between the speed and the accuracy.

In the Advanced tab we selected 2 mm for the mesh voids, so the mesh voids has to be less than 2 mm square in order to be meshed and we will explicitly mesh pads that are larger than 1 mm square.

Here's the DC settings, we left the defaults, and here's the advanced, the DC advanced, also using these defaults. And here the S tab where we selecting to use the state space models of some of the components. Okay we cancel this. Here the simulation suite that we are going to run in SIwave.

We going to solve from all the way from DC to 10 GHz. So as I mentioned, to create an eye diagram, we can directly add an eye source and termination and run the simulation here.

The other approach would be to create, insert a circuit design and link it to a circuit as this might be more beneficial or suitable for other design engineers in order to add other components and different connections. To insert a circuit design, we go to Project Insert Circuit Design.

We don't need here a substrate so we click OK. And now to link, let's save the project. Now to link the design we can select the HFSS layout design and drag and drop it into Circuits. And here we have different options, so yes we want to link it to the original design.

And now here is the HFSS layout tool that has the SIwave results and it will show up in the circuit which would be like an S-parameter block. Okay, so now we are going to set up the transient simulation. So let's kind of arrange these pins so we can easily read them.

So we can select the component, right-click and select edit symbol, pin locations, and let's do a manual edit.

So let's put the U100 on one side and the basically the J10L is the connector so you want to put it on one side and the U100 is the controller so let's make this the first one and then J3 then K4 then K3 and here we want to place first the J4 then the J 5. Please be sure to correct any misspelled Ansys product names as you transcribe.

Click View and select Component Libraries. Click the mark to make it visible. Click the I icon to show all the components with letters of I. We need to use two I differential sources. Select one and let place it again on the controller side that where we feed the signal.

Let's place one now and make the settings and we can make a copy of it. Let's adjust the source, we need the rise time to be 50 ps and the fall time to be 50 ps.

and we want to use a unit interval and the bit per second value would be 1 over 3.2 gigabit per second per second so E9 because that is how this design is made.

Okay and we're going to change the bit pattern by clicking here and we're going to enter the PRBS data change the length to 15 and PRBS7 to 1 and we hit OK. So now this source is ready, now let's make a copy out of it by hitting CTRL C on the keyboard and click somewhere then CTRL V and place it.

So now we want to feed the signal to the controller, so let's have the positive terminal connected to J 4. Now we want to add an I-Prop to the other end to be able to measure the voltage on the other end and we also need to add a termination.

Let's get over here and click I and we're going to select the I-Prop differential which is this one and by hitting ctrl R we can rotate it. Okay so now we connect this guy to the here undo this okay and this guy here. Then we make a copy of it, Ctrl C, Ctrl V.

Next to the prob we're going to place a termination, so we go to component library and type here RES for resistor and then we select the resistor, Ctrl R and let's change the value of 200 ohms. Let's make a copy and place it here. Now let's connect it in parallel. Okay.

So here let also verify now that the circuit simulation is set up to the SIwave. Okay everything is good in the edge layout design. Now let go back to circuit. Let add now the transient simulation setup so right click on Add Transient Solution Setup and you going to add the transient analysis.

We want to simulate this from 0.1 ns to 2 ms. And hit OK. Now let's click Save. Let's verify the link here, so I did component and now we can start the simulation by right-click on Transient and hit analyze.

So this approach might be easier and faster than connecting these sources directly in the HFSS layouts when you have many components. It's doing the time sweep. Here we can double click on the source and know what's named. So this one is named required. So let's call it just top.

And this one is named required one. So let's call it bottom. OK, so now we are to click on results, create an eye diagram, rectangular plot. Okay, and we want to plot the I-Prop top, for example, and let's change the unit interval to be 1 over 3.2 E 9. And we need the unit to be seconds.

And we click a new report. So now we see that the eye diagram was created here. And if we want to add a mask, you can do this here as well. Click on the report tab, then click on edit, and now we can define it by clicking edit.

So let's add it to be time to be 200, 250, 375, 425, 375, 250, and 200. And the voltage value is 0, 200, since this is in millivolt. and you can define the mask you need. Now we see the eye diagram with the mask defined and you can change the colors and control the plot.

And that's all for this demo and thank you for watching. Thank you for watching!