Important! Even the most current version of ADS 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-Parameters

While S-parameters are convenient to use, the frequency resolution may not be adequate for narrowband simulations and yield analysis is not possible. If the frequency resolution is inadequate or if you wish to perform a yield analysis, use our lumped element (SPICE) models.

Our 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.

After the files are unzipped, run ADS.

1. Select the S2P icon from the Data Items menu.

2. Place the generic two-port element onto the design.

3. Double click the icon and select the S-parameter file by browsing to the directory where it was saved.

4. Add a ground to the ground port and connect the S-parameters to the rest of the circuit.

Lumped Element (SPICE) Models

To model our inductors, each individual lumped element for the complete model must be placed into the schematic. Refer to the published SPICE document for the inductor you are modeling.

RF inductor models require  R2, Rvar1, L, C and R1

Power inductor models require R2, Rvar1, Lvar, C, R1 and Rvar2

For these elements to be placed properly into ADS, there cannot be any frequency dependent passive elements. These are replaced with an equation based Z1 port element. An example is provided  how to implement the Rvar1 for a rf chip inductor:

Rvar1= k1 * sqrt(freq)

The following example shows how to implement Rvar1, Lvar, and Rvar2.

To implement Lvar, use the following equation:

(2 * pi *  freq * (k3 – k4 * log(k5 * freq) * 10^-6) * j

where: 10^-6 represents µH.

Since the Lvar is only the imaginary impedance, it can be combined with Rvar1 to minimize the number of components:

Z[1,1] = Rvar1 + Lvar * j

IMPORTANT: Be sure to verify the units of the inductor. In Lvar:
mH is 10^-3

µH is 10^-6

nH is 10^-9

To place the Z1P file in the schematic:

1. Select the Z1P file from the equation based item menu.

2. Place the element on the schematic.

3. Double click the element and assign the equation to the element.

4. Replace k1 with the value from the inductor published model table.

For frequency dependent inductance (Lvar2):

1. Select the Z1P file from the equation based item menu.

2. Place the element on the schematic.

3. Double click the element and assign the equation to the element.

4. Replace k1, k3, k4, k5 with values from the published model table.

Connect the input and output of the model into the circuit and the model is complete.