Inductance3

Inductance3 is one of the measurements available in the Manage Curves dialog box of a Graph Tab. Inductance3 is the series inductance between ports 1 and 2 with all of the other ports open-circuited assuming a Pi-model. The units are based on the Inductance units setting. In the example below, the inductance3 calculation gives the value of L1+L2. Since port 3 is open-circuited, the impedance connected to port 3 is not included in the calculation. Any parasitics to ground for ports 1 and 2 are not included in the inductance calculation, although any parasitics to ground for other ports are included. This equation is valid for any number of ports. All additional ports are simply open-circuited.

This measurement is can be used for center-tapped spiral inductors, although the CT-Ldiff measurement is more commonly used for center-tapped spiral inductors. This measurement should be used when you do not wish to include the parasitics to ground from ports 1 and 2 or you have additional ports you wish to open circuit. This measurement should be used when your inductor is not going to be used in a differential mode. The CT-Ldiff measurement does include the port 1 and 2 parasitics to ground and should be used when your inductor will be used in a differential mode.

Inductance3 is computed as follows:

where Z11, Z12, Z21, and Z22 are z-parameters for ports 1 and 2. If the circuit has more the 2 ports, then ports 3 and up are open-circuited for this calculation.

Please see the Measurement Properties topic for an explanation of each field in this dialog box.