Tunable Bandpass Filter Based on Partially Magnetized Ferrite LTCC With Embedded Windings for SoP Applications

Abstract

Tunable filters that are based on ferrite materials often require large and bulky electromagnets. In this work, we present a tunable filter in the Ku-band, which is realized in multilayer ferrite LTCC substrate with embedded bias windings, thus negating the need of a large electromagnet. Also, because of the embedded windings, the bias fields are not lost at the air-substrate interface and therefore the field and current requirements are reduced by an order of magnitude as compared to the previously reported filters. A simulation strategy that uses full permeability tensor with arbitrarily directed magnetic fields has been used to model the filter on a partially magnetized ferrite substrate. Special attention has also been paid to approximate the non-uniform magneto-static fields produced by the embedded windings. The complete design is implemented in 10 layers of ferrite LTCC, making it the first magnetically tunable filter with embedded windings and extremely small size [(5 5 ) ]. The filter demonstrates a measured tunability of 4% and an insertion loss of 2.3 dB. With the small form factor, embedded windings, and low bias requirements, the design is highly suitable for compact and tunable SoP applications.Index Terms-Bandpass filter (BPF), ferrite, low temperature co-fired ceramics (LTCC), system on package (SoP).

Monolithic Integrated Design of S-Band Switched Filter Bank Based on LTCC Technology

“…Little research of monolithic integrated design of S-band switched filter bank based on LTCC technology has been reported. So firstly the design in this paper is compared with the the designs of tunable filters using different methods in [4][5][6][7]. The design in this paper offers more channels for selecting than the three-channel switched filter bank based on MEMS technology, but the size of MEMS design is the advantage that LTCC cannot achieve.…”

“…The design in this paper offers more channels for selecting than the three-channel switched filter bank based on MEMS technology, but the size of MEMS design is the advantage that LTCC cannot achieve. Compared with the designs in [5][6][7], the design in this paper has fast switched response speed. More accurate selection can be made with larger tunable range, and the good out-of-band rejection can be obtained.…”

“…In 2013, Inoue et al introduced a tunable frequency filter with an optional frequency range of 1.4 GHz to 2.7 GHz, and insertion loss is less than 3 dB by adjusting the filter geometry with MEMS technology [6]. In 2015, Arabi et al, who took advantage of the performance of LTCC material by increasing the magnetic winding method to change the electrical parameters of the filter, proposed a filter with frequency modulation of 4% and insertion loss performed better than 2.3 dB [7].…”

“…The authors in [5,6] used the method of changing the geometry of the filter to achieve frequency modulation. By changing the electrical parameters of the filter to achieve the effect of change the operating frequency is presented in [7]. In this paper, the proposed switched filter bank controls filters on-off state to achieve the purpose of frequency selection through the filters' designed upfront.…”

A compact customizable tunable EBG filter

“…Planar microstrip filters with footprints around 17 Â 20 mm 2 , 13:4 Â 25 mm filter realized in ferrite LTCC substrate, first of its kind, is proposed [7]. The filter is working in Ku-band 14.35-14.95 GHz with a small size of 5:0 Â 5:0 Â 1:1 mm 3 .…”