If you buy quality SMA connectors, the vendor should be able to supply accurate simulation models of the connector. If not, you must assume that the connector impact on the signal is not important. With that assumption, you can take a good guess at a model to use in simulation. I would start with a 50 Ohm transmission line as long as the length of the center conductor in the connector, add about 1pF capacitor to ground from the PCB connection, and about 2nH series inductor at the other end.
In LineSim, you can simply add these elements to the schematic. For BoardSim, the usage depends on what is connected to the SMA connector. Is it left open? Is it connected to a cable and another PCB? Is it connected directly to another PCB?
It is connected to another PCB via cable.
Thanks for your kind reply.
The best way to model this in BoardSim is to make a SPICE subcircuit including the SMA connector, the cable, and the connector at the other end. Then apply this SPICE subcircuit as an advanced model in BoardSim multi-board. Search for "multi-board advanced model" on SupportNet, and you should find an application note or tutorial with the details.
I have some questions here about the model you propose. The scenario is the one already mentioned: one connector, cable, another connector. With or without cable in the midle, the two connectors are connected and modeled in the SPICE model.
1. One question is, regarding at the application note/tutorial that exists on the supportnet.metor.com, if the SPICE model takes into account both connectors. For a multiboard design I received a connector SPICE model that was downloaded from the conector manufacturer web page. Since it was downloaded as model corresponiding to a single connector I guess I have to somehow take it into account twice. There is no cable between the two connectors, there is a daughter board pluged into a motherboard. How to handle such models. I mean, how to make sure it is taken into account for each individual connector?
2. And second issue, is how, in general, a connector model should look like? I mean, in case of 20 pins connector the model should have defined inside either one single pin with all properties then it will be multiplied in the editing connection interface or 20 pins therefore no need for copy paste the model in the connection editor interface for multiboard designs?
3. I have a 240 pins connector and a 36 pins spice model. Should I multiply the model in the connection editor until I have 240 pins connected? what's happening with the remaining 12 pins in the model that will have no more pins to connect to? Will they affect the simulation results?
4. Is it any way, in case I have to multiply the model to connect all the pins, to run this multiplication in a text based format? Something like the .ref file for model assignment? I couldn't figure out where the information about the connectors in multiboard projects, is stored.
5. In the attached picture, do I have to manually go and select each single connector pin on the left and conect it to the model then connect the right connector the same way in order to create the connection between connectors?
thx for your future reply
HLX_SI_connector model.JPG 107.8 KB
Some level of Spice knowledge is required to be able to understand how the vendor models the connector or connector/cable assembly. Typically there is either a read me file associated to the model or commented lines on the model explaining what the model contains and how to use it.
Usually you will get one single model for both mating connectors (male and female). That would be ready to use in HyperLynx as it is, but as you mention you will have to multiply it a couple of times. For the “remaining 12 pins” you can use another copy of your 36 pins Spice model, but it is recommended to terminate the unused pins using 50 ohms resistors to ground. This is easy to do in Spice. Of course there will be no coupling between any 36 pin section and its neighbours.
Regarding the pin mapping, yes you do have to do it manually.
how can we model imedance matching through transformer in hyperlynx.
if I know the transformers primary and secondary impedance, can I model it using transmission line in hyperlynx??
Input and output impedances do not completely characterize a transformer. You will need either a Spice model or S-parameter model from your vendor. For more info check the two links below: