Implementation of a Compact EMI Filter Array for 4G-LTE Applications on LTCC

In this paper, a mixed type material is described for the first time whereby a fully integrated electromagnetic interference (EMI) filter array in low-temperature co-fired ceramic technology is implemented. To miniaturize the size of the component and have high rejection and low insertion loss, a mixed powder material with a higher permittivity and a lower loss tangent is employed to design and fabricate the filter. The material system used in this paper is BaNd₂Ti₄O₁₂ + Ni-Cu-Zn ferrite. The addition of Bi₂O₃ reduces the sintering temperature to below 900 °C. A compact EMI filter array architecture that has a wide rejection band and sufficient isolation is also introduced. For the development of wireless communications, the spectrum for global 4G-Long Term Evolution (LTE) covers different frequencies within 700-2600 MHz. In this paper, an EMI filter array that rejects unwanted frequencies from 700 to 2700 MHz, which covers all 4G-LTE bands, is presented. The EMI filter array is 1.6 mm (L)×0.8 mm (W)×0.5 mm (H), the smallest reported so far. The measured results of the developed filter are in good agreement with the simulated results by a fullwave electromagnetic simulator.