In this paper, we propose a vectorized noncircular MUSIC (VNCM) algorithm based on the concept of the coarray, which can construct the difference and sum (diff–sum) coarray, for direction finding of the noncircular (NC) quasi-stationary sources. Utilizing both the NC property and the concept of the Khatri–Rao product, the proposed method can be applied to not only the ULA but also sparse arrays. In addition, we utilize the quasi-stationary characteristic instead of the spatial smoothing method to solve the coherent issue generated by the Khatri–Rao product operation so that the available degree of freedom (DOF) of the constructed virtual array will not be reduced by half. Compared with the traditional NC virtual array obtained in the NC MUSIC method, the diff–sum coarray achieves a higher number of DOFs as it comprises both the difference set and the sum set. Due to the complementarity between the difference set and the sum set for the coprime array, we choose the coprime array with multiperiod subarrays (CAMpS) as the array model and summarize the properties of the corresponding diff–sum coarray. Furthermore, we develop a diff–sum coprime array with multiperiod subarrays (DsCAMpS) whose diff–sum coarray has a higher DOF. Simulation results validate the effectiveness of the proposed method and the high DOF of the diff–sum coarray.

This article presents a dual-core quad-mode orthogonal-coupled wide frequency tuning range voltage-controlled oscillator (VCO) using mode control switches to realize the even/odd mode selection. Each core of the VCO adopts a parallel 8-shaped coil structure to avoid the influence of the other orthogonal-coupled one. Together with capacitor banks and varactors, the combination of orthogonal-coupled VCO cores demonstrates an extremely wide frequency tuning range on the basis of the existing range expanding from the dual-mode. The proposed VCO can be classified into two cases with different applications. One is that only one oscillation frequency is required; thus, four modes together show a wide frequency range. The other is that two different oscillation signals can be provided at the same time. The VCO has a measured tuning range of 8.3–21.7 GHz for the combination of low-and high-band cores. It consumes 4–6 mW with a measured phase noise of $-$ 127 dBc/Hz at a 10-MHz offset from a carrier of 9.6 GHz, and the FoM and FoM $_{\mathrm{T}}$ are $-$ 179 and $-$ 199 dBc/Hz, respectively. The VCO is designed and implemented in the 65-nm complementary metal-oxide-semiconductor (CMOS) technology with a die area of 0.4 mm $^{2}$ .

This letter presents a new strategy for the formation of continuous Cu seed layer in high aspect ratio (HAR) through-silicon-vias (TSVs) with large depth based on sequential sputtering and electroless plating. The deposited seed layer is continuous and dense even at the bottom of the TSVs, which is difficult to achieve by individual sputtering or electroless plating. Combined with the spin coating of polyimide (PI) liner, atomic layer deposition (ALD) of TiN barrier layer, and electroplating of Cu conductor, TSVs with diameter of $9~\mu \text{m}$ and depth of $141~\mu \text{m}$ are successfully fabricated, and the aspect ratio is 15.5. The TSVs are fully filled without cracks or voids, proving the good quality of seed layers. Electrical measurements show that the minimum capacitance of a single TSV is around 145 fF, and the leakage current is about 3.4 pA at 20 V, indicating good electrical properties of the fabricated TSVs and the feasibility of the proposed fabrication flow in deep HAR TSV applications.

The low earth orbit (LEO) satellites have received extensive attention as an essential supplement to the terrestrial network for supporting global Internet of Things (IoT) services. Considering the rapid growth of IoT devices and the significant satellite-to-ground latency, proposing low-latency, low-overhead access protocols for LEO satellite IoT systems is challenging. In this article, we propose a multibeam random access (RA) framework and deploy the deep reinforcement learning (DRL) algorithm to control the nonorthogonal multiple access (NOMA) aided RA strategy. First, we divide the satellite coverage region into multiple beams and assume that the adjacent beams share parts of regions. Hence, the devices in the sharing region are allowed to transmit packets in two periods allocated for the two beams. Then, packets in multiple beams can be decoded jointly by an interslot successive interference cancelation (SIC) decoder. In addition, we consider the heterogeneity among devices and assign different power levels for heterogeneous types of devices, which enables power-domain NOMA and the intraslot SIC decoder in this system to mitigate the collision resolution. To maximize the average throughput, the deep deterministic policy gradient (DDPG) algorithm is adopted to achieve an online decision to optimize the RA protocol where the packet repetition strategies of devices are adjusted dynamically. The simulation results show that the proposed scheme outperforms the traditional benchmark schemes with significant throughput gain.

Flexible photodetectors have attracted much attention due to their great potentials in wearable electronics, bendable image sensors, and environmental monitoring, which requires functional components with good machinal properties. Herein, we introduced a novel metallic two-dimensional (2D) material, MXene, to form the electrodes by a spray-coating method and zero-dimensional (0D) PbS quantum dots (QDs) to work as photoactive layer. All solution-processable fabrication technique contributes to a simplified, low-cost and large-scale route to develop flexible photodetectors. Benefiting from the excellent conductivity of MXene electrodes and broadband photoresponse of PbS QDs, our devices realize a high detectivity up to $2.4\times10$ ¹¹ Jones and exhibit good stability even after 1000 bending cycles. This work provides a new device configuration with 2D electrodes and 0D photoactive layers for designing high-performance flexible electronics.

Recently, the concept of the difference and sum co-array (DSCa) has attracted much attention in array signal processing due to its high degree of freedom (DOF). In this paper, the DSCa of the nested array (NA) is analyzed and then an improved nested configuration known as the diff-sum nested array (DsNA) is proposed. We find and prove that the sum set for the NA contains all the elements in the difference set. Thus, there exists the dual characteristic between the two sets, i.e., for the difference result between any two sensor locations of the NA, one equivalent non-negative/non-positive sum result of two other sensor locations can always be found. In order to reduce the redundancy for further DOF enhancement, we develop a new DsNA configuration by moving nearly half the dense sensors of the NA to the right side of the sparse uniform linear array (ULA) part. These moved sensors together with the original sparse ULA form an extended sparse ULA. For analysis, we provide the closed form expressions of the DsNA locations as well as the DOF. Compared with some novel sparse arrays with large aperture such as the NA, coprime array and augmented nested array, the DsNA can achieve a higher number of DOF. The effectiveness of the proposed array is proved by the simulations.