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Ideal Transformer with Center Tap (Closed Form): XFMRTAP; XFMRTAP2


Equivalent Circuits

The following figures display the difference between the XFMRTAP and XFMRTAP2 models.

The major difference between the XFMRTAP and XFMRTAP2 models is the manner in which the primary coil affects the secondary coils. In the XFMRTAP model, the entire primary coil is seen by both of the secondary coils, so changing the turn's ratio for one coil does not affect the voltage at the other coil. In this case, it is equivalent to three coils in parallel, not really a center tap at the output coil. In the XFMRTAP2 model, a fraction of the input coil is seen by the two secondary coils, so changing the turn's ratio for one coil affects the output voltage of both coils.

You can change the turn's ratios and observe what happens in both scenarios, then use the transformer that is appropriate for your application.


Name Description Unit Type Default
ID ID Text X1
N1 Sec1:pri turns ratio   1
N2 Sec2:pri turns ratio   1

Implementation Details

Implements an ideal transformer with primary coil between nodes 1 and 2 and two secondary coils between nodes 3 and 4 and between nodes 4 and 5. The ratio of secondary to primary turns is given by N1 and N2. "Ideal" means that DC is also transformed with this element. If you do not want to transform DC, you need to add capacitors on either side of the model to block DC.


This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

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