I need to know resistor’s parasitic values to consider in EM simulations. Please share the same for part number - WR04X1000FTL. It would be okay if I get SPICE Model of the same.
Welcome to the Digikey tech forum. I put in a request for the information and will post when I get it.
The apparent parasitics of low-value chip resistors tend to be strongly influenced by their specific implementation; things like pad geometry, board material, and stackup can change the effective values quite significantly.
If you’re attempting simulations at a level where those parasitics matter, you’d probably want to develop a model that represents your specific conditions so as not to waste your time putting garbage into the simulator and getting garbage out. As a very rough starting point however, the solder pads might present something like a half pF of capacitance to the ground plane each, while lifting the signal off the board surface and onto the top of the resistor body might add something like a half nano henry of series inductance.
Thanks for the response @rick_1976. That was helpful.
It would be good if you have any manufacturer who provides the parasitic info of a resistor. I could find the SPICE models for Capacitors/ inductors but not for resistors. Also, up to which frequency range we can ignore the parasitic of a resistor with value ~100-200 Ohms?
I can’t recall ever seeing a supplier provide spice models for an SMT resistor. To the extent that the parasitics are dependent on user-selected parameters, it would be quite difficult to do so in any meaningful way.
One can often find models for capacitors and inductors because these components are quite terrible by comparison, in ways that are defined by the component itself rather than its placement on a PCB. For example, a resistor’s R value doesn’t collapse by 80% simply because a person applies a few volts of DC bias across it. A ceramic capacitor with a class II dielectric does exactly that sort of trick however, hence the need for a model.
Were a person speaking of wirewound resistors or an axial thin film that might have a spiral trim pattern, some extra inductance could be expected. A thick film 0402 however is probably one of the closer things we have to a component that behaves like its ideal model.
Sorry the delay on this but the manufacturer asked the following question:
I would like to know the required frequency in hertz in order to share the SPICE model.
Can you provide this information ?