Bangchao Yang

Compact Second-Order LTCC Substrate Integrated waveguide Filter with Two Transmission Zeros

Abstract A compact second-order substrate integrated waveguide (SIW) filter using low-temperature co-fired ceramic (LTCC) technology with two transmission zeros for high-selectivity application is presented. The proposed filter is composed of a Modified Doublet (MD) and input/output (I/O) SIW. The MD comprises two resonators that are not coupled to each other, whereas the two resonators are placed below and above the I/O SIW, respectively. The input and output SIW are directly coupled in order to generate up to two finite transmission zeros. The filter not only has good selectivity owing to the controllable transmission zeros by tuning the coupling manner and strength between the I/O SIWand two resonators, but also has a small size by profit from LTCC structure. A demonstration filter having a center frequency of 10 GHz and a 3 dB fractional bandwidth of 2.5% is designed and fabricated to validate the proposed structure. The measured results exhibit high selectivity, minimum passband insertion loss of 2.09 dB, and in-band return loss greater than 14 dB, agree well with simulated ones. Furthermore, based on the vertically multilayer structure using LTCC technology, the overall size of the filter is only 18 × 10 × 1.2mm3.

Miniaturized mixed-cross coupling bandpass filter with source–load coupling

A miniaturized trisection bandpass filter (BPF) with improved stopband characteristics is presented. The proposed BPF consists of three stepped impedance resonators (SIRs), where the nonadjacent SIRs share a common shorted stub, and the other SIR is embedded inside the nonadjacent SIRs. To improve frequency selectivity, mixed-cross (M-C) coupling and source–load (S–L) coupling were introduced in the nonadjacent resonators and source/load ports, respectively. Owing to the M-C and S–L couplings, multiple transmission zeros (TZs) can be employed for high skirt selectivity and upper wide stopband. A new BPF centered at 2.45 GHz with 17.6% fractional bandwidth has been designed and fabricated to verify the validity of the proposed method. The measurement result shows four finite TZs in the stopband, located at 2.09, 2.98, 4.64, and 12.47 GHz, respectively. The circuit only occupies 6.70 × 8.60 mm2

A novel DC-DC convertor using LTCC technology for magnetic integration application

A compact DC-DC convertor is proposed and fabricated in multilayer ferrite substrate using LTCC technology. The spiral conductors are buried into the ferrite substrate with a multilayer 3-D structure to reduce the volume of convertor. The passive integration of magnetic components and surface circuitry are achieved in a whole substrate and the size of module can be reduced markedly. The whole height of module is only 3mm, 1/3 of the height of conventional modules. Testing results indicate that the performance of the module is excellent in Point-of-Load (POL) field. The step-down DC-DC converter converts input voltage of 5V to output voltage of 3.3V. It is confirmed that the maximum conversion efficiency of 93.2% is sufficient for actual DC-DC converter application. Such a compact DC-DC convertor provides a compact, low cost and high reliability approach for power supply and magnetic integration application.

Preparation and Dielectric Properties of Cerium and Manganese Codoped Ba0.6Sr0.4TiO3 Ferroelectric Films

Cerium (Ce) and manganese (Mn) codoped Ba0.6Sr0.4TiO3 (BST) films were prepared by improved sol-gel method and the effect of preheating on their dielectric properties was investigated. X-ray diffraction (XRD) reveals that the films grow principally along (110) orientations and show cubic perovskite structures. Preheating corresponds to smaller FWHMs, stronger crystallization and larger grain sizes, and preheating with codoping corresponds to the smallest FWHM, the strongest crystallization and the largest grain size. The prepared film can show tunability of 55.7%, dielectric loss of 0.0074∼0.0175 and approximately 75 FOM, meeting the needs of tunable microwave applications.

Miniaturized Bandpass Filter with Improved Stopband

Abstract In this article, a miniaturized bandpass filter with improved stopband using a short-circuit centered stepped impedance resonator is presented. An extra transmission zero can be provided near the passband for good frequency selectivity by introducing mixed electric/magnetic coupling in the proposed filter. Multiple transmission zeros are introduced in the upper stopband via, taking advantage of the harmonic effects of the distributed transmission line. Meanwhile, source-load coupling is introduced to improve the skirt selectivity via shifting the transmission zeros to the vicinity of the passband. The odd- and even-mode analytical method is used to design the filter. To verify the validity of the proposed technique, the new bandpass filter has been analyzed, simulated, and fabricated. The measurement results agree well with the full-wave electromagnetic designed responses.

Compact LTCC module for WLAN RF front-end

In this paper, a low-temperature co-fired ceramic (LTCC) module for Wireless Local Area Network (WLAN) RF front-end is proposed. The module integrates an embedded band pass filter, an embedded lumped element Wilkinson power divider, and embedded LTCC inductors and capacitors, in a single LTCC package. The circuit is separated into low-frequency circuit part and high frequency circuit part. By integrating these miniature passive component designs, using the three-dimensional multichip module multichip module (3D-MCM) technique, the proposed module features a compact size of 20mm×20mm×5mm. The measurement results show that the application meets the current electrical specification requirements of the wireless communication system compatible with IEEE802.11b/g.

Compact radar altimeter simulator using low temperature co-fired ceramic technology

A low-temperature co-fired ceramic (LTCC) module for miniaturized radar altimeter simulator is presented in this paper. By taking advantages of the LTCC three-dimensional Multi-chip Module (3D-MCM) technology, the embedded circuit elements can be arranged vertically for size reduction. The proposed module features a compact size of 25mm × 24mm, with a packaged height of 5.5mm.