Generation of ultra-short pulses using the Wilkinson adder

In this work the possibility of increasing the amplitude of ultra-short pulses and formation of a monocycle Gaussian by adding signals from several oscillators was investigated. For this purpose, the ring adders of Wilkinson design were used. The design of which has been chosen due to low losses and high input decoupling. The S-parameters of the adders with different geometrical parameters have been simulated in the frequency band up to 5 GHz. The obtained results coincided with the experimentally measured characteristics. The monopulse amplitude was increased and a bipolar pulse shape was formed by adding ultrashort pulses of equal and different polarities using the adders. This approach allows you to adjust the parameters of the output signal by adjusting the delays of the triggering signals.

Minimized Triple-Band Eight-Element Antenna Array for 5G Metal-frame Smartphone Applications

A multiple-input-multiple-output (MIMO) antenna array for triple-band 5G metal-frame smartphone applications is proposed in this paper. Each single antenna element consists of an S-shaped feeding strip and an L-shaped radiation strip on the metal frame. The dimension of the antenna element is only 6.5 mm × 7 mm (0.076 λ0 × 0.082 λ0, λ0 is the free-space wavelength at the frequency of 3.5 GHz). The −6 dB impedance bandwidth of the proposed eight-antenna array can cover 3.3–3.8 GHz, 4.8–5 GHz, and 5.15–5.925 GHz. The evolution design and the analysis of the optimal parameters for a single antenna element are derived to investigate the principle of the antenna. The measured total efficiency is larger than 70%. The measured isolation is better than 13 dB. The measurements of the prototype agree well with the simulation results.

Timepix4, a large area pixel detector readout chip which can be tiled on 4 sides providing sub-200 ps timestamp binning

Timepix4 is a 24.7 × 30.0 mm2 hybrid pixel detector readout ASIC which has been designed to permit detector tiling on 4 sides. It consists of 448 × 512 pixels which can be bump bonded to a sensor with square pixels at a pitch of 55 µm. Like its predecessor, Timepix3, it can operate in data driven mode sending out information (Time of Arrival, ToA and Time over Threshold, ToT) only when a pixel has a hit above a pre-defined and programmable threshold. In this mode hits can be tagged to a time bin of <200 ps and Timepix4 can record hits correctly at incoming rates of ∼3.6 MHz/mm2/s. In photon counting (or frame-based) mode it can count incoming hits at rates of up to 5 GHz/mm2/s. In both modes data is output via between 2 and 16 serializers each running at a programmable data bandwidth of between 40 Mbps and 10 Gbps. The specifications, architecture and circuit implementation are described along with first electrical measurements and measurements with radioactive sources. In photon counting mode X-ray images have been taken at a threshold of 650 e− (with <10 masked pixels). In data driven mode images were taken of ToA/ToT data using a 90Sr source at a threshold of 800 e− (with ∼120 masked pixels).

Радиопоглощающие свойства феррит-полимерных композитов поливиниловый спирт/Ni-Zn феррит

The electromagnetic and radio-absorbing characteristics of ferrite-polymer composites with conductive inclusions based on polyvinyl alcohol are investigated. The Ni-Zn spinel ferrite powder of 2000NN grade with composition Ni0.32Zn0.68Fe2O4 was used as filler. It is shown that the obtained composites are effective absorbers in the frequency range of 2⸺5 GHz with peak reflection loss less than –20 dB. Through the analysis of the permittivity spectra and permeability spectra, as well as the calculated reflection loss spectra, critical factors of the electromagnetic wave absorption in obtained composites are established.

Operation Features of a Coaxial Virtual Cathode Oscillator Emitting Electrons in the Outer Radial Direction

The operation features of the coaxial virtual cathode oscillator emitting electrons in the outer radial direction were investigated through simulations and experiments. A coaxial vircator was compared with an axial vircator when the anode to cathode distance of both vircators was 6 mm. The proposed coaxial vircator was operated when the anode to cathode distance was 5 mm, 6 mm, and 7 mm. The peak power and frequency of the microwave generated from the proposed coaxial vircator when the anode to cathode distance was 6 mm were 20.18 MW and 6.17 GHz, respectively. The simulations and experiments show that the proposed coaxial vircator generates 80% more microwave power than the axial vircator with the same anode to cathode distance. According to the simulations and experiments, the proposed coaxial vircator tends to generate a higher power average when the anode to cathode distance was larger than 5 mm. The frequency of the proposed coaxial vircator when the anode to cathode distance was 5 mm and 7 mm was approximately 8 GHz and 5 GHz, respectively. The geometric factor of the proposed coaxial vircator was considered to be the reason for the greater microwave power generation than the axial vircator. The frequency of the proposed coaxial vircator decreases inversely proportional with the anode to cathode distance as observed in the axial and basic coaxial vircators.

Enhanced ablation efficiency for silicon by femtosecond laser microprocessing with GHz bursts in MHz bursts (BiBurst)

Ultrashort laser pulses confine material processing to the laser-irradiated area by suppressing heat diffusion, resulting in precise ablation in diverse materials. However, challenges occur when high speed material removal and higher ablation efficiencies are required. Ultrafast burst mode laser ablation has been proposed as a successful method to overcome these limitations. Following this approach, we studied the influence of combining GHz bursts in MHz bursts, known as BiBurst mode, on ablation efficiency of silicon. BiBurst mode used in this study consists of multiple bursts happening at a repetition rate of 64 MHz, each of which contains multiple pulses with a repetition rate of 5 GHz. The obtained results show differences between BiBurst mode and conventional single pulse mode laser ablation, with a remarkable increase in ablation efficiency for the BiBurst mode, which under optimal conditions can ablate a volume 4.5 times larger than the single pulse mode ablation when delivering the same total energy in the process.

Modified 16-Quasi Log Periodic Antenna Array for Microwave Imaging of Breast Cancer Detection

In this paper, an effective system for microwave imaging of breast tumor detection using modified 16-planar log periodic antenna (PLPA) array is presented. The modified PLPA operates in the band from 2 to 5 GHz with stable directional patterns in the end-fire direction. Once the results of a single antenna element have been validated, the design is extended to include 16 antenna elements. All 16 transceiver antennas are vertically placed around the phantom in a circular manner where one antenna acts as a transmitter and the rest work as receivers. Delay and Sum (DAS) algorithm is used for post processing the acquired scattered signals from the sensors to reconstruct the image of the breast and to identify the existence of breast tumors. The electromagnetic simulators CST and HFSS are used to design the system, while MATLAB is used to process the data. The developed PLPA array-based microwave imaging system performs admirably, making it one of the most effective systems for detecting tumor cells.

A Low-Power Squaring Circuit with Regulated Output and Improved Settling Time in 180 nm CMOS for 3–5 GHz IR-UWB Applications

This paper demonstrates a low-power squaring circuit for 3–5 GHz non-coherent Impulse-Radio Ultra-Wideband (IR-UWB) receivers for Pulse Position Modulation (PPM) in a low-cost 180 nm CMOS technology. The squaring, which is the key element in typical IR-UWB receivers, is performed exploiting the non-linear transfer function of a MOS transistor. For a high gain at low power consumption the transistor is biased in the moderate inversion region, where the second-order derivative of the transconductance gm and, as a result, the quadratic term in the transfer function reaches a maximum. A control loop was implemented to set the dc output voltage to a defined value and thus to allow a comparison of the squarer output signal with a defined threshold voltage, which can easily be set and adjusted (e.g. by a DAC). To speed up the settling time of the output and hence to reach higher data rates, a novel slew-rate booster is implemented at the output. Thereby, the squarer is capable of data rates of up to 15.6 Mbit s−1, which is more than two times higher compared to the circuit without the slew-rate booster, while only consuming 72.4 µW in addition. In the extracted post-layout simulations the whole circuitry consumes 724 µA at a 1.8 V power supply, resulting in a power consumption of 1.3 mW.

FAST continuum mapping of the SNR VRO 42.05.01

The relativistic electrons rotate in the enhanced magnetic field of the supernova remnants and emit the synchrotron radio emission.We aim to use the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to obtain a sensitive continuum map of the SNR VRO 42.05.01 (G166.0+4.3) at 1240 MHz. The 500 MHz bandwidth is divided into low and high-frequency bands centered at 1085 and 1383 MHz to investigate the spectral index variations within the remnant, together with the Effelsberg 2695 MHz data. We obtained an integrated flux density of 6.2±0.4 Jy at 1240 MHz for VRO 42.05.01, consistent with previous results. The spectral index found from TT-plot between 1240 and 2695 MHz agrees with previous values from 408 MHz up to 5 GHz. The three-band spectral index distribution shows a clear flatter value of α ∼ −0.33 in the shell region and steeper index of α = −0.36 − −0.54 in the wing region. The flatter spectral index in the shell region could be attributed to a second-order Fermi process in the turbulent medium in the vicinity of the shock and/or a higher compression ratio of shock and a high post-shock density than that in elsewhere.

AlN/GaN MISHEMTs on Si with in-situ SiN as gate dielectric for power amplifiers in mobile SoCs

AlN/GaN metal-insulator-semiconductor high electron mobility transistors (MISHEMTs) on silicon substrate using in-situ SiN as gate dielectric were fabricated and their RF power performance at mobile system-on-chip (SoC) compatible voltages was measured. At a mobile SoC-compatible supply voltage of Vd = 3.5 V/5 V, the 90-nm gate-length AlN/GaN MISHEMTs showed a maximum power-added efficiency (PAE) of 62%/58%, a maximum output power density (Poutmax) of 0.44 W/mm/0.84 W/mm and a linear gain of 20 dB/19 dB at the frequency of 5 GHz. These results suggest that the in-situ-SiN/AlN/GaN-on-Si MISHEMTs are promising for RF power amplifiers in 5G mobile SoC applications.