Rolled-up transformer structure for a radiofrequency integrated circuit (RFIC)
A rolled-up transformer structure comprises a multilayer sheet having a rolled configuration comprising multiple turns about a longitudinal axis. The multilayer sheet comprises more than one conductive pattern layer on a strain-relieved layer, including a first conductive film and a second conductive film separated from the first conductive film in a thickness direction. The first conductive film comprises an even number of primary conductive strips, where each primary conductive strip has a length extending in the rolling direction, and the second conductive film comprises an even number of secondary conductive strips, where each secondary conductive strip has a length extending in the rolling direction. In the rolled configuration, turns of the primary conductive strips and turns of the secondary conductive strips wrap around the longitudinal axis. The primary conductive strips serve as a primary winding and the secondary conductive strips serve as a secondary winding of the rolled-up transformer structure.
1. A rolled-up transformer structure for a radiofrequency integrated circuit (RFIC), the rolled-up transformer structure comprising:
a multilayer sheet in a rolled configuration comprising multiple turns about a longitudinal axis, the multilayer sheet comprising a conductive pattern layer on a strain-relieved layer, the conductive pattern layer comprising a first conductive film separated from a second conductive film in a rolling direction,
wherein the first conductive film comprises an even number of primary conductive strips, each of the primary conductive strips having a length extending in the rolling direction,
wherein the second conductive film comprises an even number of secondary conductive strips, each of the secondary conductive strips having a length extending in the rolling direction,
wherein, in the rolled configuration, the primary conductive strips wrap around the longitudinal axis and the secondary conductive strips wrap around the primary conductive strips, the primary conductive strips being a primary winding and the secondary conductive strips being a secondary winding of the rolled-up transformer structure.
2. The rolled-up transformer structure of claim 1 , wherein the primary conductive strips are separated from the secondary conductive strips on the strain-relieved layer by a distance g v of from about 30 microns to about 100 microns.
3. The rolled-up transformer structure of claim 1 , wherein the primary conductive strips comprise at least about 20 turns about the longitudinal axis.
4. The rolled-up transformer structure of claim 1 , wherein the secondary conductive strips comprise at least about 10 turns about the primary conductive strips.
5. The rolled-up transformer structure of claim 1 , wherein the length of each of the primary conductive strips is at least about 70 microns.
6. The rolled-up transformer structure of claim 1 , wherein the length of each of the secondary conductive strips is at least about 10 microns.
7. The rolled-up transformer structure of claim 1 , wherein the primary conductive strips overlap with the secondary conductive strips in the rolled configuration.
8. The rolled-up transformer structure of claim 1 , wherein the primary conductive strips are interconnected, and wherein the secondary conductive strips are interconnected.
9. The rolled-up transformer structure of claim 1 , wherein the first conductive film further comprises two conductive feed lines connected to end portions thereof, the two conductive feed lines extending away from the first conductive film in the rolling direction.
10. The rolled-up transformer structure of claim 1 , wherein a ratio of a thickness of the conductive pattern layer to an inner diameter of the rolled configuration is about 0.005 or greater.
11. The rolled-up transformer structure of claim 1 , wherein the conductive pattern layer comprises a high conductivity material selected from carbon, silver, gold, aluminum, copper, molybdenum, tungsten, zinc, palladium, platinum and nickel.