Design of 94GHz High Efficiency Rectifier MMIC

This paper introduces a physical intrinsic model of terahertz frequency planar Schottky diodes. Using this model, 591 sets of reverse current-voltage (I-V) characteristic data that cover the common physical parameters of GaAs Schottky mixer diodes in the terahertz band were generated and aligned to construct a dataset for deep learning analysis of diode electrical properties. The reverse I-V characteristics of GaAs Schottky Barrier Diodes (SBDs) under different physical parameters were investigated. The results show that the anode diameter, epitaxial layer thickness, and doping concentration of the diodes have different impacts on the reverse I-V characteristics of GaAs Schottky diodes, providing an important reference for the design and optimization of Schottky diodes in terahertz applications.

Nonlinear acoustics allows for applications like tissue harmonic imaging in medicine and parametric arrays in underwater acoustics. Mainstream sonars transmit and receive signals at the same frequency and up to now energy transferred to higher harmonic frequencies has been mainly seen as a disturbance for target strength estimation, e.g., in fishery research. This paper investigates the feasibility of utilizing the part of the signal generated around the second harmonic frequency band by nonlinear propagation of sound in water. It presents the potential enhancements the second harmonic signal may provide for target imaging as well as multifrequency target recognition. It compares measurements of the pressure field radiated by commercial transducers in water at 121 and 200 kHz up to a range of 12 m with numerical simulations. The detected levels of higher harmonic signals agree with simulations of nonlinear wave propagation. This verifies the implementation of the simulator and allows a comparison of the beam characteristics at longer ranges when filtered around the fundamental or second harmonic frequencies. An example of pulse-echo imaging with spherical targets is also shown using signals at the fundamental and second harmonic frequencies where the second harmonic signal can detect one of the targets that the fundamental signal cannot. Using the active sonar equation to estimate the maximum range, simulations based on a simple model including ambient noise and volume reverberation confirm that with a source level of 228 dB and a detection threshold of 12 dB the fundamental signal at 200 kHz can detect a fish of target strength -36 dB to approximately 343 m while the detection range of the second harmonic signal is approximately 243 m. The combined use of the signal components in the second harmonic and fundamental frequency bands provides a high-resolution image at short range and a long-range imaging capability at a lower resolution as well as a multifrequency characterization of targets.

In this article, a quasi-elliptic wideband bandstop filter (BSF) is presented with the proposed synthesis theory. In order to analyze the novel mechanism of creating extra two reflection zeros (RZs) in back-to-back open-ended spanner structure, both without coupling structure (BSF I) and with coupling structure (BSF II) are analyzed and discussed in detail where BSF I consists of two open stubs, two cascaded transmission lines (TLs), and a stepped-impedance open stub, which is shunted in the center of the filter; by dividing the stepped-impedance open stub into two coupled line (CL) sections, BSF I becomes BSF II, which includes a back-to-back open-ended spanner structure. The proposed synthesis theory proves that BSFs I and II belong to the same theoretical quasi-elliptic response transfer function. Considering the urgent needs of design specifications for BSF, the proposed synthesis theory could directly design and control the stopband with equal-ripple performance, such as the fractional bandwidth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{21}$ </tex-math></inline-formula> (FBW<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{S_{21}}$ </tex-math></inline-formula>) and stopband rejection of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{21}$ </tex-math></inline-formula> (SR). After design theory, flowchart and design charts are summarized and discussed, and six design examples are also selected for theoretical verification. Furthermore, by inserting <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2N$ </tex-math></inline-formula> TLs in the center of the proposed filter, extra <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2N$ </tex-math></inline-formula> RZs can be generated accordingly. Because of limited pages, only two selected examples are listed for demonstration. Finally, two fabricated circuits for BSFs I and II are fabricated at 1 GHz for experimental demonstration. Excellent agreement between the simulated and measured results is achieved so as to successfully prove the proposed synthesis theory.

A compact wideband high-rejection microstrip bandstop filter (BSF) is presented. This filter combines two traditional BSFs: open-stub filter and spurline filter. Due to the inherently compact characteristics of the spurline, the proposed filter shows a better rejection performance than open-stub BSF without increasing the circuit size. From 3.7 to 5.4 GHz, the proposed BSF has a rejection of better than 20 dB and the maximum rejection level of 61 dB. Application of this BSF to suppress the second harmonic of an open-loop ring bandpass filter is also investigated with a 40-dB suppression improvement achieved.

A novel planar bandstop filter with high insertion loss is proposed. With the assistance of coupled lines with open stubs at the input and output ports, the newly proposed structure is different from the conventional bandstop filter. With the coupled lines mentioned above, selectivity and stopband rejection of the newly proposed planar bandstop filter can be effectively enhanced. Moreover, the attenuation level of the proposed structure can be controlled by adjusting the resonant frequency of each resonator. Design equations can be obtained with the assistance of the lossless transmission line model and parallel coupled-line model. In order to validate the analysis, a bandstop filter, with a fractional bandwidth of 14% for the measured stopband at 50 dB, is fabricated.

In this paper, a quadruple-push oscillator is proposed for the first time. The quadruple-push oscillator consists of four identical sub-circuits and a microstrip ring resonator. By using the ring resonator as common resonator, the four identical sub-circuits oscillate in the same fundamental frequency f/sub 0/, and the fundamental oscillating signal of each sub-circuit has a phase difference of 90/spl deg/, 180/spl deg/ and 270/spl deg/ to that of the others. Therefore, the undesired fundamental signals (f/sub 0/), the second harmonic signals (2f/sub 0/), the third harmonic signals (3f/sub 0/) and so on can be suppressed in principle and the desired fourth harmonic signal (4f/sub 0/) is obtained when all the signals are combined. A Ka-band quadruple-push oscillator was designed and fabricated. The measured output power of the desired fourth harmonic signal (4f/sub 0/) was +1.67 dBm at the frequency of 35.8 GHz. The measured suppression of the undesired signals of the fundamental signal (f/sub 0/), the second harmonic signal (2f/sub 0/), the third harmonic signal (3f/sub 0/) and the fifth harmonic signal (5f/sub 0/) were -18.0 dBc, -17.9 dBc, -17.8 dBc and -35.5 dBc, respectively. The measured phase noise performance at 35.8 GHz was -104.0 dBc/Hz at an offset frequency of 1 MHz.

In order to solve the shortcomings of wireless passive sensors based on label chips for signal transmission, which cannot withstand high temperatures, and the problem of the short transmission distance of wireless passive sensors without chips, a wireless passive high-temperature frequency-doubling microstrip antenna sensor based on a high-temperature-resistant Schottky diode is proposed. The sensor utilizes the characteristic of the resonant frequency of the microstrip antenna changing with temperature. The high-temperature-resistant platinum sensitive structure integrated on alumina ceramic adapts to temperature measurement in harsh environments such as high temperatures, oxidation, and corrosion. A high-temperature-resistant Schottky diode was designed, and on this basis, a high-temperature-resistant frequency doubling circuit was designed and implemented. Through this circuit, the network analyzer can transmit a fundamental frequency signal and receive a modulated double frequency signal, while limiting ambient noise to the fundamental frequency band, eliminating interference, and significantly improving the signal-to-noise ratio, thereby enabling wireless transmission. In addition, a high-temperature-resistant, miniaturized broadband coplanar waveguide antenna was designed to replace the traditional horn antenna as the interrogation antenna, which realized the wireless transmission of sensor signals. A high-temperature testing system was set up to test the sensor performance in the range of 15–800 °C. The results showed that the maximum transmission distance of the sensor is 20 cm, and the transmission performance is best at 10 cm away from the interrogation antenna. It can accurately characterize the temperature during the heating process, with a sensitivity of up to 181 KHz/°C and a frequency error of no more than 0.2%.

This paper presents a through-type harmonic transponder for S-band nonlinear radar. To increase the operating frequency range, a 2-stage L-shaped matching network was configured for the input and output matching networks. In previous studies, conventional harmonic transponders were configured with λ/4 stubs in the input and output matching networks to minimize the influence of these networks because the impedance mismatch suppresses the second harmonic and fundamental signals. However, in this design, a λ/4 open stub was utilized at the output and configured with the output matching network to alleviate the insertion loss of the additional open stub. For verification, the proposed circuit was implemented with the circuit size of 37.6 mm×16.1 mm. The measurement results show that the conversion gain is maintained over −15 dB for frequencies between 2.8~3.8 GHz at −5.5 dBm and −17.5~11 dBm at 3.1 GHz of input power.

The article deals with the technology of estimating the frequency of harmonic components in the presence of additive normal interferences for solving applied problems of spectral analysis. Objective: to develop a methodology for the synthesis of algorithms for determining the frequency of a complex harmonic signal in discrete sections of the process, this is observed when using data segmentation. Objective: to develop the optimal technology for determining the frequency of the hormonal component of the process, provided by a finite number of discrete compartments, according to model representations and requirements that meet the problems of the current state of spectral analysis practice. These results were obtained. The problem of estimating the harmonic frequency from segmented data in the presence of additive Gaussian interference in observations based on the method of maximum likelihood is solved. The processing algorithm and the consequences of digital modeling of the synthesized evaluation technology for a given number of discrete process samples are given. The analysis of both the practical capacity of the technology for determining the assessment and certain qualitative indicators of assessment is performed. Conclusions. The scientific novelty of the obtained results is as follows: further development as a method for solving problems of estimating the frequency of the harmonic signal from a few sample values of the process under conditions of additive normal interference and methods for optimizing the structure of digital processing of observations in data segmentation. The synthesized technology uses one sample of observations to determine the estimates, which ensure the efficiency of information processing in a simple software implementation. The use of segmentation in the technological process of digital processing of observations allows obtaining estimates, the quality of which corresponds to the indicators of maximum likelihood. For unambiguous assessment, there is a need to eliminate ambiguity. Under these conditions, the technology with a given number of samples can significantly solve the range of signal-to-noise ratios at which can be obtained unbiased estimates.

Second harmonic imaging: Good reverberations

50 nm Schottky kontak kalınlığına sahip Ni/n-GaAs Schottky diyotlarınınakım-gerilim (I-V) verileri 60 K’den 320 K’e kadar olan geniş bir sıcaklıkaralığında ölçüldü. Ni/n-GaAsSchottky diyotlarının önemli kontak parametreleri geleneksel I-Vmetodu, Norde metodu, genelleştirilmiş Norde metodu ve Cheung fonksiyonlarıkullanılarak her bir sıcaklık değeri için ayrı ayrı elde edildi. Daha sonrasonuçlar birbirleriyle kıyaslandı.

Reverse-bias currentnvoltage (IRnV ) characteristics of Al-n / GaAs Schottky diodes have been studied in a temperature range from 92 to 333 K. The results are explained on the basis of phonon-assisted tunnelling model. It is shown that the temperature dependence of the reverse current IR could be caused by the temperature dependence of the electron tunnelling rate from traps in the metalnsemiconductor interface to the conduction band of the semiconductor. Temperature-dependent IRnV data obtained by Zhang et al [J. Appl. Phys. 2006; 99: 023703] and Osvald et al [Microelectron. Eng. 2005; 81: 181] for Schottky diodes fabricated on n-GaN are reinterpreted in terms of a phonon-assisted tunnelling model. The temperature and bias voltages dependences of an apparent barrier height (activation energy) observed by other researchers are also explained in the framework of this model.

Can Fourier transform mass spectral resolution be improved by detection at harmonic multiples of the fundamental ion cyclotron orbital frequency?

Harmonic signal generation and frequency upconversion at millimeter-wave bands are experimentally demonstrated by using selective sideband Brillouin amplification induced by stimulated Brillouin scattering in a single-mode fiber. The harmonic signals and frequency upconverted signals are simultaneously generated by the beating of optical sidebands, one of which is Brillouin amplified. By using this method, we successfully demonstrate generation of third-harmonic millimeter waves at 32.55 GHz with f(LO) of 10.85 GHz and upconversion of 10 Mbps quadrature-shift keyed data at f(IF) of 1.55 GHz into a 30 GHz band with more than 17 dB RF power gain.

&amp;lt;p&amp;gt;Harmonic tremor, ground vibrations captured by seismometers oscillating in different frequencies, has been widely identified as a result of distinct physical processes. In volcanic areas, the physical processes to explain the gliding spectral lines are usually identified preceding/accompanying eruptions. Less is known about harmonic tremor that occurs in active volcanic areas but does not end in an eruption.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;In this study we analyse a harmonic tremor signal with a spectral behaviour that, to our knowledge, has not previously been observed. We observed the harmonic signal in the vertical component spectrogram of 22 out of the 24 broad-band seismometers placed around and within Torfaj&amp;amp;#246;kull caldera, in Iceland. The discovery was made while estimating a tomographic image of the volcano using a network of seismometers operating for nearly 3 months in summer 2005. a function of frequency and time, the detected harmonic signal has a parabola structure (or a &amp;amp;#8216;V&amp;amp;#8217; shape) with a fundamental frequency and a few overtones exhibiting higher energy. The fundamental mode glides upward from frequencies below 1Hz up to and above 25 Hz and can take up to 10h from the minimum to the maximum achieved frequency. A few low and high-frequency tremors also occurred during the gliding of the harmonic signal.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;In an exploratory phase, we ruled out phenomena of anthropogenic (drilling, helicopters) and natural non-volcanic origins (colliding ice structures, tidal, magnetic field, rain, wind, aurora) due to the time and frequency characteristics of the signal. We then analyzed the temporal and spatial distribution of the harmonic tremors (signal of interest). Automatic detection was leading to a large number of false positives and true negatives, therefore we performed a manual classification of daily spectrograms to detect the &amp;amp;#8216;V&amp;amp;#8217; shaped signal. We select the events where the high amplitude spectra were reaching below 2 Hz. The occurrence and strength of the harmonic signal are variable in time and space. The spatial density of signal occurrence does not correlate with the location of the source of subsidence we estimate from InSAR; the detected subsidence of ~13 mm/year is confined to the caldera outline while the harmonic events were registered mostly at seismometers outside the volcano caldera. The detected signal does correlate well with areas of low topography and identified low-velocity S-wave anomalies from the derived ambient noise seismic tomography model using the same seismic network. While the correlation with low topography may indicate preferred water paths, the low S-wave velocity anomalies may indicate the presence of a heat source, leading to a water-magma interaction hypothesis. Finally, we tested for the hypothesis of a resonance set up in magmatic conduits after magma-water interaction and changes in speed flow through conduits assuming the geometries of dykes, tubes and cracks.&amp;lt;/p&amp;gt;