In this study, polyvinyl alcohol (PVA)-mixed DL-alanine (PVA/DL-alanine) polycrystals are fabricated, and their piezoelectric characteristics in the d₃₃ mode are investigated. The d₃₃ piezoelectric coefficients of the PVA/DL-alanine polycrystals are found to increase with an increase in the weight ratio of DL-alanine, and the PVA/DL-alanine polycrystal composed of PVA and DL-alanine in a weight ratio of 1:3 exhibits a d₃₃ of ∼5 pC/N. The piezoelectric characteristics of the PVA/DL-alanine polycrystals are discussed in terms of the crystal structure by employing scanning electron microscopy and X-ray diffraction analyses. To confirm the piezoelectric performance of the polycrystals, the piezoelectric voltages of a piezoelectric device composed of a single layer of ZnO thin film and heterostructured devices consisting of a layer of PVA/DL-alanine polycrystal and a ZnO thin film layer are measured and compared. This study presents PVA/DL-alanine polycrystals as a potential piezoelectric material for bio-friendly piezoelectric-device applications.

A wideband low‐noise amplifier (LNA) for long‐term evolution applications is presented. A capacitive cross‐coupled common‐gate in combination with current‐bleeding common‐source topologies is adopted for wideband input matching, high gain and low noise figure (NF). Inter‐cascade inductors are adopted to cancel the inter‐stage parasitics, which extend input matching and operational bandwidth to higher frequency with additional NF reduction. Implemented in a 0.18 µm CMOS technology, the proposed wideband LNA shows a voltage gain of 17 dB, a NF of < 2.5 dB, | S ₁₁ | of higher than 10 dB and a maximum IIP3 of + 1.52 dBm over the frequency range of 0.7–2.7 GHz while consuming 7.5 mA from a 1.8 V supply.

In this letter, we present a method to design an elevation beam pattern mask for spaceborne synthetic aperture radar (SAR) to reduce the range ambiguity. The proposed two-way elevation beam pattern mask, which requires relatively low sidelobe levels only in the direction of strong range ambiguous echoes, can be highly suitable for enhancing the range ambiguity to signal ratio (RASR). The power levels of the different ambiguous echoes are estimated based on the backscattering coefficient model and satellite geometry. To meet the two-way beam pattern mask, both transmit and receive beam patterns are synthesized simultaneously through the minimax algorithm. To confirm the effectiveness of this mask design method, the RASR performance is evaluated by using various swaths.

Recently, SnSe material with an outstanding high ZT (Figure of merit) of 2.6 has attracted much attention due to its strong applicability for highly efficient thermoelectric devices. Many studies following the first journal publication have been focused on SnSe materials, not on thermoelectric devices. Particularly, to realize highly efficient intermediate-temperature (600~1000 K) thermoelectric modules with this promising thermoelectric material, a more thermally and electrically reliable interface bonding technology needs to be developed so that the modules can stably perform their power generation in this temperature range. In this work, we demonstrate several approaches to develop metallization layers on SnSe thermoelectric legs. The single-layer metallization shows limitations in their electrical contact resistances and elemental diffusions. The Ag/Co/Ti multi-layer metallization results in lowering their electrical contact resistances, in addition to providing more robust interfaces. Moreover, it is found to maintain the interfacial characteristics without any significant degradation, even after heat treatment at 723 K for 20 h. These results can be effectively applied in the fabrication of thermoelectric devices or modules that are made of the SnSe thermoelectric materials.

This paper presents a highly cost-effective design for an aluminum (Al) foil-based ZnO/Ag/ZnO-stacked piezoelectric nanogenerator (ZAZ-NG) fabricated using radio frequency magnetron sputtering. Both Al foil sheets and a silver (Ag) paste layer are utilized to make a ZAZ-NG composed of an Ag paste layer sandwiched between two zinc oxide (ZnO) layers. The output voltages of the ZAZ-NGs with various ZnO thicknesses are measured for three different bending strains. As a result, the devices could generate a relatively high peak-to-peak output voltage (V_pp) of up to 2.5 V, which is 28 times higher than that of the single ZnO layered device. In addition, the device performance shows a strong dependence on the thickness of the ZnO layer. Moreover, the ZAG-NG device is structurally stable and can be fabricated using cost-effective methods.