Resistance3

Resistance3 is one of the measurements available in the Manage Curves dialog box of a Graph Tab. Resistance3 is the series resistance (in ohms) between ports 1 and 2 with all of the other ports open-circuited assuming a Pi-model. The units are based on the Resistance units setting. In the example below, the resistance3 calculation gives the value of R1+R2. 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 measurement can be used for center-tapped spiral inductors, although the CT-Rdiff 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 resistor is not going to be used in a differential mode. The CT-Rdiff measurement does include the port 1 and 2 parasitics to ground and should be used when your resistor will be used in a differential mode.

Resistance3 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.