Thin-Film Integrated Passive Device Technology Based Ultraminiaturized Bandpass Filter for 5G Communication Application

In this paper, an ultraminiaturized Thin-Film Integrated Passive Device (TFIPD) band-pass filter (BPF) is designed and analyzed for the n77 band of 5G communication application. The proposed BPF offers several characteristics such as low-profile structure, easy onboard integration, and low loss device, which is suitable to incorporate in the RF front-end system. TFIPD technology process offers a higher level of integration, which is desirable to integrate the proposed BPFs with other microwave chips at a system in package system level. In the design of BPF, the Chebyshev filter structure is adopted in which a pole-zero is introduced to generate a notch structure. The pole-zero is obtained by adding capacitance, inductance to the resonant circuit structure, which also improves the steep-drop performance of BPF and adjusts the passband width. The proposed BPF structures are designed using lumped spiral inductor and metal-insulator-metal (MIM) capacitor elements. The lumped inductor is designed using an air bridge structure-based spiral inductor, which avoids the parasitic effects generated by the through-hole structure, and the lumped capacitor is designed using a MIM capacitor, which makes the design simpler and more convenient. The measurement results of the TFIPD BPF resonates at n77 (3.3-4.2 GHz) band offers IL{min} of 0.706 dB, IL{max} of 1.540 dB, return loss of 26.901 dB, and transmission zero at 2.913 GHz@16.923 dB, 5.722 GHz@53.401 dB. The physical characteristic of the BPF is low profile with a dimensional size of 1.51\times 1.33\ \text{mm}^{2}.