For the convenience of illustration, the planar transformer as shown in
The winding 310 comprises conductive paths R2, R4, R6, and R8, and the winding 320 comprises conductive paths R1, R3, R5, and R7. The conductive paths R1˜R8 surround a position point PP. Herein, the winding 310 and the winding 320 are substantially alternatively disposed on the same plane, as shown in
In consideration of the coupling effect of the transformer 300 and the substrate, the distance between the transformer 300 and the substrate must be extended as much as possible. In the present embodiment, the winding 310 and the winding 320 are, for example, disposed in the top metal layer.
Since the winding 310 and the winding 320 are alternatively disposed on the same plane and the winding 310 and the winding 320 are not electrically connected to each other, the cross parts 311, 312, 313, 321, 322, and 323 are disposed in the transformer 300. In each of the cross parts, two electrical paths that are not electrically connected to each other must be disposed in the different planes. For example, when the first electrical path (connected to the conductive path R6) of the cross part 311 is disposed on the top metal layer, the second electrical path (connected to the conductive path R8) of the cross part 311 is disposed in the metal layer beneath the top metal layer, and the second electrical path of the cross part 311 is connected to the conductive path R8 in the top metal layer through the via.
In the present embodiment, the first winding 310 further comprises an electrical connection portion 330. The electrical connection portion 330 is disposed in the pad layer. The pad layer is disposed above the top metal layer. Usually, the pad layer is used to form the bonding pad. The material of the pad layer can be different from that of the metal layers thereunder. For example, the material of the metal layers can be copper (or copper compound), and the material of the pad layer can be aluminum or aluminum compound. Since the electrical connection portion 330 is disposed in the pad layer, the efficiency of the planar transformer 300 is not affected. The electrical connection portion 330 is electrically connected to the conductive paths R2 and R4, thus forming the complete first winding 310.
As required, a central lead is disposed in the first winding 310 or the second winding 320 of the transformer 300. For example, a first lead 340 is disposed to make the lead being electrically connected to the center tap node of the first winding 310 (herein, the center tap node is just at the electrical connection portion 330), as shown in
The winding 410 comprises the conductive paths R2, R4, R6, and R8, and the winding 420 comprises the conductive paths R1, R3, R5, and R7. As shown in
In the present embodiment, the first winding 410 further comprises the electrical connection portions 430, 431 and 432. The electrical connection portions 430 and 431 are disposed in the pad layer. Since the electrical connection portions 430 and 432 are disposed in the pad layer, the efficiency of the planar transformer 400 is not affected. The electrical connection portions 432 are electrically connected to the conductive paths R4, and the electrical connection portions 430 and 431 are electrically connected to the conductive paths R2, and R4, thus forming the complete first winding 410 (the number of turns is 3).
As required, a central lead is disposed in the first winding 410 or the second winding 420 of the transformer 400. For example, a first lead 440 is disposed to make the lead being electrically connected to the center tap node of the first winding 410 (herein, the center tap node is just at the electrical connection portion 430), as shown in
The winding 510 comprises the conductive paths R2, R4, R6, and R8, and the winding 520 comprises the conductive paths R1, R3, R5, and R7. As shown in
In the present embodiment, the first winding 510 further comprises the electrical connection portions 530, 531, 532, and 533. The electrical connection portions 530˜533 are disposed in the pad layer. Since the electrical connection portions 530˜533 are disposed in the pad layer, the efficiency of the planar transformer 500 is not affected. The electrical connection portion 530 is electrically connected to the conductive paths R6 and R8, the electrical connection portion 531 is electrically connected to the conductive paths R6 and R2, the electrical connection portion 532 is electrically connected to the conductive paths R4 and R8, and the electrical connection portion 533 is electrically connected to the conductive paths R2 and R4, thus forming the complete first winding 510 (the number of turns is 2).
As required, the central lead can be disposed in the first winding 510 or the second winding 520 of the transformer 500. For example, the first lead 540 is disposed to make the lead being electrically connected to the center tap node of the first winding 510 (herein, the center tap node is just at the electrical connection portion 533), as shown in
The winding 610 comprises the conductive paths R2, R4, R6, and R8, and the winding 620 comprises the conductive paths R1, R3, R5, and R7. As shown in
In the present embodiment, the first winding 610 further comprises the electrical connection portions 631, 632, and 633. The electrical connection portions 631˜633 are disposed in the pad layer. Since the electrical connection portions 631˜633 are disposed in the pad layer, the efficiency of the planar transformer 600 is not affected. The electrical connection portions 631 and 632 are electrically connected to the conductive paths R2, R4, R6, and R8, thus forming the complete first winding 610 (the number of turns is 1).
As required, the central lead can be disposed in the first winding 610 or the second winding 620 of the transformer 600. For example, the first lead 640 is disposed to make the lead being electrically connected to the center tap node of the first winding 610 (herein, the center tap node is just at the electrical connection portion 633), as shown in
To sum up, the present invention makes use of the connection part disposed in the pad layer to flexibly determine the turn ratio of the transformer. In the planar transformer of the present invention, the first winding and the second winding can be alternatively disposed on the same plane with any turn ratio. In the present invention, the connection part disposed in the pad layer can also be used to reduce the number of the cross parts between the transformer and the metal layer.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.