Development of co-planar thin film transformer with high frequency transmission characteristics

利用微细光刻技术在柔性聚酰胺薄膜上制作了共面薄膜变压器。共面薄膜变压器由两条铜带线组成。铜带线的宽度和厚度分别为100微米、17微米和100微米。研究了在柔性聚酰胺薄膜上制作的共面薄膜变压器在MHz到GHz的很高频率范围内的特性。在10~1300 MHz频率范围内，测量了柔性聚酰胺薄膜共面薄膜变压器的传输特性，并进行了数值模拟。实验传输特性在400 MHz和800 MHz附近有两个平缓的峰值。在峰值频率下，透过率超过90%，在300~900 MHz之间的透过率超过-6分贝(50%)。在900 MHz以下的频率范围内，计算值与实验值吻合较好。在900 MHz以上，实验值再次上升，引发另一次共振。但由于铜线的电阻增大，导致损耗增大，计算值逐渐减小。在10~1300 MHz频率范围内，测量了夹有镍锌铁氧体的共面薄膜变压器的传输特性。共面变压器互感的增大导致了低频段透过率的上升。但在高频段的透过率随频率的增加而减小。

A co-planar thin film transformer was fabricated using micro lithography on a flexible polyamide film. The co-planar thin film transformer was made of two copper strip lines. A width and thickness of copper strip line and a distance between two copper lines were 100mum, 17mum and 100mum, respectively. The co-planar film transformer which has been fabricated on a flexible polyamide film was studied in a very high frequency range of MHz to GHz. The transmission characteristic of co-planar thin film transformer on a flexible polyamide film was measured in the frequency range of 10 MHz to 1300 MHz and also was simulated. The experimental transmission characteristic have two gentle peaks around 400 MHz and 800 MHz. At peak frequencies the transmission over 90% was obtained and also the transmission between 300 MHz and 900 MHz was over-6 dB (50%). In frequency range of under 900 MHz, the calculated values agreed well with the experimental value. Over 900 MHz the experimental values rose again for another resonance. But the calculated value gradually decreased for the increase of a loss which was attributable to increase of electrical resistance of copper line. The transmission characteristic of co-planar film transformer sandwiched with NiZn ferrites was measured in the range of 10 MHz to 1300 MHz. The increase of a mutual inductance of co-planar transformer caused a rise in the transmission in low frequency range. However the transmission in high frequency range decreased with a increase of frequency.