This paper presents a multibeam patch antenna array fed by Rotman lens based on substrate integrated suspended line (SISL) platform. With the advantages of low cost, self-packaging, and wide angle scanning, the proposed antenna can be applied for 24GHz automotive anti-collision radar system. The SISL Rotman lens with sixteen input ports is employed as the beam-forming network (BFN) to generate a corresponding number of beams. With the SISL’s advantages of low loss, even if all substrates use only very cheap FR4 to reduce cost, good lens performances can still be maintained at 24GHz. By utilizing double metal layers with metalized via hole connecting and cutting the undesired substrate, the loss of lens can be further reduced. Moreover, the design of Rotman lens involves tradeoff considerations for wide angle scanning. The radiating part consists of sixteen patch antennas, which are designed using SISL technology for broadband operation and high gain. The experimental results demonstrating a scanning range of ±44° at 24GHz, illustrate that the multibeam antenna array has been successfully demonstrated.
for 5μm diameter micro bumps, the interfacial intermetallic compounds (IMCs) seriously affects the interconnection performance of micro bumps. In this paper, we focused on the discussion of the growth and control mechanism of IMCs of 5um diameter micro bumps at different temperatures and durations. The growth mechanism and morphology of Ni3Sn4 IMC was studied. Through the EDS analysis of the cross-sectional micro bumps, it could be determined that the composition of the slender columnar crystal IMC was Ni3Sn4. When the heating temperature was higher than the melting point of Sn-3.0wt%Ag solder, the IMC would exhibit uneven and abnormal growth along the Sn grain boundary. Furthermore, the IMC growth and diffusion mechanisms of solid-solid and solid-liquid interface reaction were discussed respectively. Finally, based on the temperature and duration of the growth and evolution of the Ni3Sn4 IMC, we gave appropriate suggestions for the use of small-sized micro bumps.
In this paper, a silicon-based high-integration frequency reconfigurable monopole is designed. This antenna is designed on silicon wafer, and all manufacturing steps are completely compatible with silicon process. This method can integrate silicon-based antenna into communication system easily. To further improve the antenna’s integration, an optimized band stop filter is introduced into the antenna system to replace the conventional capacitor and inductor, and measurement results confirm the usefulness of this filter. Based on these results, the designed monopole achieved two frequency configurations at 3.23GHz and 4.48GHz, and other radiation parameters are also shown good results.
In modern optical communications, pulse amplitude modulation 4 (PAM4) is employed to achieve higher data rates than that achieved by conventional non-return-to-zero format. Meanwhile, there is an increasing interest to convert wired connections to wireless in data centers using high-speed millimeter-wave and terahertz (THz) links. Here, we introduced the PAM4 modulation for THz wireless communications using a resonant tunneling diode (RTD) receiver. Compared with a Schottky-barrier diode receiver, the RTD receiver has higher sensitivity, and a stronger nonlinearity at low input power when it is operated with an amplified detection scheme. We achieved 24-Gbaud (48-Gbit/s) transmission in the 300-GHz band with a quasi-real-time digital signal processing (DSP), which is the fastest PAM4 wireless communication without an offline DSP to the best of our knowledge.
We experimentally demonstrated a silicon optical isolator using a monolithically integrated cobalt ferrite (CFO) film as magneto-optical material, achieving an isolation ratio of 9.6dB near 1550nm wavelength. By virtue of the large Faraday rotation coefficient of CFO, the device has a compact footprint comparing to the current yttrium iron garnet-based isolators. Furthermore, we demonstrated self-biased isolation by the strong remanence of CFO films, eliminating the tedious demand of an external magnet. Cobalt ferrite represents a potential alternative approach to yttrium iron garnets to realize a practical device for on-chip isolation in silicon photonic integrated circuits because of the small footprint.
A quantum voltage noise source (QVNS) based on the Josephson effect as a reference signal is indispensable in precise Johnson noise thermometry (JNT) because it provides quantum accurate power spectral density (PSD) represented by some physical constants and design parameters. An integrated QVNS (IQVNS) device that integrates the circuit elements required for generation of a QVNS signal into one chip has been developed at AIST. The PSD of IQVNS should be variable for precise JNT measurement over a wide temperature range. Here, a new IQVNS device with variable PSD--programmable IQVNS--was developed and the values of the PSD were experimentally confirmed to be consistent with the theoretical values for various design parameters. Thus, JNT measurement over a wide temperature range can be realized with the IQVNS.
This letter proposes a fast simplified successive-cancellation (FSSC) polar decoder architecture, supporting any code rate. With the parameter M, which is the maximum limit length of a special polar node, the authors present a novel scheme for online identification of special node in a polar code. In addition, under the parameter M, the proposed decoder has a well optimized architecture to reduce area, power and energy consumption, that due to require less internal memory using cross-layer calculation and less hardware resources for special node without pipeline technology. Synthesis and post-layout simulate results, based in TSMC 65nm CMOS technology, show that the consumption of hardware resources is reduced by 25%. The architecture and circuit techniques reduce the power to 54.9mW for an energy efficiency of 77.22 pJ/b.
This paper proposes a frequency hopping method of multiple insertions of frequency points (MIFP) to shorten the lock time of fractional-N Phase-locked loop (PLL) in the large frequency hopping (FH) interval mode. Several frequency points between initial frequency and desired-frequency are inserted to steer the frequency up or down (multiple small FH step instead of direct large FH interval), which can ensure that the response processes are linear under-damped. The transient response process of PLL is theoretically analyzed and the feasibility of this method is verified by simulation. Moreover, this method is applied on radar local oscillators (LOs). Measurements show that 8us of the frequency hopping time can be reduced by using MIFP method compared with traditional direct frequency hopping from 2.0GHz to 2.8GHz with the loop bandwidth of 200kHz.
An automatic detection system for distinguishing healthy, ictal, and inter-ictal EEG signals is of importance in clinical practice. This paper presents a low-complexity three-class classification VLSI system for epilepsy and seizure detection. The designed system consists of a discrete wavelet transform (DWT)-based feature extraction module, a sparse extreme learning machine (SELM) training module, and a multiclass classifier module. A lifting structure of Daubechies order 4 wavelet is introduced in three-level DWT to save circuit area and speed up the computational time. The SELM which is a novel machine learning algorithm with low hardware complexity and high-performance is used for on-chip training. One-against-one multiclass non-linear SELM is designed for the first time due to its high classification accuracy. The designed system is implemented on an FPGA platform and evaluated using the publicly available epilepsy dataset. The experimental results demonstrate that the designed system achieves high accuracy with low-dimensional feature vectors.