Implementing Models in Microwave OfficeImportant! Even the most current version of Microwave Office may not contain up-to-date libraries of our inductor models and S-parameters. Coilcraft provides the most current and accurate versions of our models on our web site. S-parametersOur S-parameters are provided in a single compressed "zipped" file. The file must be "unzipped" after downloading to obtain the separate inductor value S-parameter files. You can either link to or import our S-parameter data files. To place the data file on a schematic: Lumped element (SPICE) modelsTo model our chip inductors, either select the CCIND element from the Lumped Element - Inductor menu or place each individual lumped element for the model onto the schematic. An example chip inductor schematic is shown in Figure 1. Figure 1. Example schematic for a Coilcraft chip inductor
Figure 2. Example schematic for a Coilcraft power inductor
For a frequency-dependent resistance (RVAR1, RVAR2)Note: This example uses RVAR1 ( = k1 * sqrt(Frequency)). For a frequency-dependent inductance (LVAR)Note: This element is used in some of our power inductor models. Graphing specific model inductance and Q resultsImportant! Our models represent de-embedded measurements in which fixture parasitic reactances have been removed. Fixture (or circuit board) parasitic reactances raise the effective impedance (and the effective inductance), lower the self-resonant frequency (SRF), and shift the Q curve. For the most accurate model of our inductors in your specific circuit environment, you must include your circuit board model in the simulation. InductanceTo view the effective series inductance of the model in a graph: Quality factor (Q)Q values and curves in our data sheets are typically based on measurements using an impedance analyzer in a 50 Ohm environment, giving a 1-port (reflection) measurement result. If Q calculations are to be compared with data sheet values and curves, they should be based on a simulation with one port of the inductor model connected to ground (as shown in Figure 2). If you are interested in the Q of the inductor in a 2-port series configuration, the additional 50 Ohms impedance of the second port results in a lower simulated Q value than the 1-port configuration. This result is logical considering that the additional 50 Ohms applies to the "Re [Z]" in the denominator of the Q calculation equation. Q = Im [Z] / Re [Z] At this time, Microwave Office does not have a Q measurement function. You must enter the equation for Q in the "Output Equations" window.
Im [Z] output equation1. Open the "Output Equations" window. Re [Z] output equation1. Open the "Output Equations" window. Q equation1. Open the "Output Equations" window. To view the Q vs. frequency of the model in a graph1. Right click on the graph name, and click "Add Measurement." |
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