YU Ting-ting, LI Da-shan, ZHANG Zi-xuan, PU Jia-cheng, LIU Bao-guang
Computer & Telecommunication.
2025, 1(12):
51-54.
With the rapid development of flexible electronics, wearable devices, and implantable medical electronics, traditional rigid filters can no longer meet the requirements of new electronic systems due to their inability to adapt to dynamic bending conditions and poor spatial compatibility. To address the above issues, a flexible LC filter is proposed. The proposed structure is implemented on a low-cost flexible printed circuit board (FPCB). The introduction of coupled capacitors significantly reduces the device size and loss; in addition, the design of the double-helical inductor reduces the required area and loss, greatly improves the integrability, and enhances the bending reliability. Furthermore, two resonant networks (R1 and R2) form a second-order filtering response through coupled capacitors, thereby constructing the flexible filter and achieving the goals of high spatial compatibility and low loss. Finally, through fabrication and testing, the proposed flexible filter has a center frequency of 11.4 MHz, a 3 dB fractional bandwidth of 19.93%, and an actual insertion loss of 1.52 dB at the center frequency.