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In this paper, we present the design and performance evaluation of a prototype device based on gain-driven polariton, which can function as an amplifier. This device can outperform a single microwave cavity in terms of phase noise and stability. Employed as a standalone amplifier, it demonstrates consistency between input and output phase noise, achieving a gain of up to 35 dB with a typical output of 5 dBm at 4.26 GHz. Despite its limited bandwidth, the device provides an effective solution for small signal amplification, ensuring minimal noise introduction. [ABSTRACT FROM AUTHOR]

A numerical model describing a magnonic active ring oscillator (MARO) based on a microscopic spin-wave delay line is proposed. The model considers excitation, propagation, and reception of the magnetostatic surface waves in a yttrium iron garnet (YIG) magnetic film with a thickness in the nanometer range. The waves are excited and received with a microscopic coplanar antenna. We employed the model to analyze the influence of the YIG-film thickness and the distance between the antennas on the MARO performance characteristics. We showed that an increase in the delay time inserted by the delay line reduces the phase noise of the MARO and increases the auto-oscillation threshold. In addition, we found a relation between the auto-oscillation threshold, the thickness of the YIG film, and the distance between the antennas. The relation helps design miniature MAROs and suggests a way to reduce the phase noise of the device. The model predicts a phase noise level of −115 dBc/Hz at a 10 kHz offset from an oscillation frequency in the vicinity of 5 GHz for the MARO based on a 100 nm-thick YIG film and 56 μm of distance between the coplanar nano-antennas of the YIG-film based delay line. We believe that this is a clear way forward to microminiaturize the time-delay feedback microwave auto-oscillators. A further reduction in the phase noise down to −125 dBc/Hz at a 10 kHz offset is found in a model of cascaded connection of several microscopic spin-wave delay lines. [ABSTRACT FROM AUTHOR]

To establish ubiquitous and energy-efficient wireless sensor networks (WSNs), short-range Internet of Things (IoT) devices require Bluetooth low energy (BLE) technology, which functions at 2.4 GHz. This study presents a novel approach as follows: a fully integrated all-digital phase-locked loop (ADPLL)-based Gaussian frequency shift keying (GFSK) modulator incorporating two-point modulation (TPM). The modulator aims to enhance the efficiency of BLE communication in these networks. The design includes a time-to-digital converter (TDC) with the following three key features to improve linearity and time resolution: fast settling time, low dropout regulators (LDOs) that adapt to process, voltage, and temperature (PVT) variations, and interpolation assisted by an analog-to-digital converter (ADC). It features a digital controlled oscillator (DCO) with two key enhancements as follows: ΔΣ modulator dithering and hierarchical capacitive banks, which expand the frequency tuning range and improve linearity, and an integrated, fast-converging least-mean-square (LMS) algorithm for DCO gain calibration, which ensures compliance with BLE 5.0 stable modulation index (SMI) requirements. Implemented in a 28 nm CMOS process, occupying an active area of 0.33 mm2, the modulator demonstrates a wide frequency tuning range of from 2.21 to 2.58 GHz, in-band phase noise of −102.1 dBc/Hz, and FSK error of 1.42% while consuming 1.6 mW. [ABSTRACT FROM AUTHOR]

An optoelectronic oscillator (OEO) system is built up with a high-speed silicon microring modulator. The modulator is based on a p-n doped ring resonator with a radius of 10 μm. Its electro-optic (EO) 3 dB bandwidth is ∼31.7 GHz, which makes it suitable for generating multi-GHz radio frequency signals. By using this modulator, one of the essential components of an OEO, the EO converter, has been dramatically miniaturized. At the same time, assisted by the ring resonator, the phase noise of the generated 10 GHz signal (nearly −90 dBc/Hz at 10 kHz offset) is not compromised compared to other integrated OEOs with mm footprint modulators. This is an important step toward a compact, scalable, and fully integrated silicon photonics-based OEO system together with our existing integrated light sources and photodetectors. [ABSTRACT FROM AUTHOR]

This article comprehensively reviews and studies CMOS transformer tank voltage‐controlled oscillators (VCOs) designed to improve the frequency tuning range (FTR) and minimize phase noise (PN) across a broad frequency range, particularly for mm‐wave and fifth‐generation applications. The study focuses on enhancing the performance of the oscillators to meet the demanding requirements of these advanced applications. This study thoroughly investigates and compares various strategies to increase the FTR, minimize PN, and reduce power dissipation in transformer tank VCOs. The aim is to establish fundamental guidelines for implementing transformer‐based tank VCOs. The study comprehensively reviews and analyzes the overall architecture of transformer‐based tank VCOs, presenting a detailed examination of the methods employed to enhance VCO performance. Additionally, the study illustrates the impact of the coupling factor on the VCO's performance parameters, detailing and demonstrating the overall tank circuit quality factor (Q) and resonator coupling factor (κ). A thorough understanding of PN methodology and the limitations of FTR has led to the development of innovative architectures. These include transformer‐based capacitive feedback (FB) oscillators with resistively adjusted variable inductors, as well as class‐F and inverse class‐F VCOs. These novel architectures contribute significantly to the improvement of oscillator performance. [ABSTRACT FROM AUTHOR]

Aiming at the characteristics that the signal noise ratio (SNR) gradually decreases from the near to far range of the swath, an adaptive phase filtering algorithm based on Goldstein filtering and combined with multiple quality-guided graphs was proposed. Firstly, the components used to determine the filtering parameters were obtained through residue density, pseudo-coherence coefficient and pseudo-SNR, the three quality-guided graphs. Then, the filter parameters were calculated by weighting the three components. Finally, the size of filtering window was determined according to the account of residues, and the interferometric phase noise was removed in frequency domain. Simulated data, TSX/TDX data and airborne interferometric imaging radar altimeter data were used to verify the performance of the new algorithm. Compared with the results of Goldstein filtering and its improved algorithms, the results showed that the proposed algorithm can effectively filter out phase noise while maintaining the edge characteristics of interferometric fringe. The section of filtering result can well match with the section of simulated pure interfeometric phase. Moreover, the algorithm proposed in this paper can effectively remove the noise in the interferogram of TSX/TDX sea ice data, and the residues' filtering rate was above 86%, which can effectively remove the phase residues of the sea ice surface while maintaining the characteristics of the sea ice edge. Experimental results showed that the new algorithm provides an effective phase noise filtering method for imaging radar altimeter data processing. [ABSTRACT FROM AUTHOR]

During the modulation process of the VSI motor drive system, the nonlinear errors caused by the dead-time and conduction voltage drop will increase the phase current harmonic distortion and the torque ripple. To solve this problem, a novel dead-time free modulation scheme is proposed in this paper. In the non-zero crossing region of the phase current, the switching tube, whose body diode can provide a continuation path, is set as off-state, the driving signal is only implemented on another switching tube with the same bridge arm, and the errors caused by the conduction voltage drop and switching delay are compensated to the pulse duration. At the same time, to suppress the zero current clamp effect that exists near the zero crossing point of the phase current, another modulation scheme for the phase current crossing zero in advance is proposed, which avoids the complicated determination and calculation of the current polarity near the zero crossing point of the current. Both of the above modulation schemes eliminate the dead-time, and the switching principle is presented. In addition, to suppress the impact of the current ripple and high-frequency noise on the accuracy of the phase current detection, a second-order resonance digital filter without phase shift is introduced. Finally, compared to two deadtime compensation methods, the effectiveness and superiority of the proposed dead-time free modulation scheme are verified by the experimental results. [ABSTRACT FROM AUTHOR]

With the gradual expansion of mining scale in open-pit coal mines, slope safety problems are increasingly diversified and complicated. In order to reduce the potential loss caused by slope sliding and reduce the major threat to the safety of life and property of residents in the mining area, this study selected two mining areas in Xinjiang as cases and focused on the relationship between phase noise and deformation. The study predicts the specific time point of slope sliding by analyzing the dynamic history correlation tangent angle between the two. Firstly, the time series data of the micro-variation monitoring radar are used to obtain the small deformation of the study area by differential InSAR (D-InSAR), and the phase noise is extracted from the radar echo in the sequence data. Then, the volume of the deformation body is calculated by analyzing the small deformation at each time point, and the standard deviation of the phase noise is calculated accordingly. Finally, the sliding time of the deformation body is predicted by combining the tangent angle of the ratio of the volume of the deformation body to the standard deviation of the phase noise. The results show that the maximum deformation rates of the deformation bodies in the studied mining areas reach 10.1 mm/h and 6.65 mm/h, respectively, and the maximum deformation volumes are 2,619,521.74 mm3 and 2,503,794.206 mm3, respectively. The predicted landslide time is earlier than the actual landslide time, which verifies the effectiveness of the proposed method. This prediction method can effectively identify the upcoming sliding events and the characteristics of the slope, provide more accurate and reliable prediction results for the slope monitoring staff, and significantly improve the efficiency of slope monitoring and early warning. [ABSTRACT FROM AUTHOR]

Summary: This paper presents more compatible three‐stage inverter‐based ring voltage controlled oscillators (VCOs) by modifying the current‐starved delay cell to oscillate with high tuning range. Unlike some ring structures in which extra transistors are used as current boosting to enhance the frequency tuning range, no extra elements are used in the proposed three‐stage VCOs for increasing the tuning range. Besides, a new method is introduced to couple two proposed ring VCOs for designing a six‐phase ring VCO. The coupling method can be generalized to some other ring VCOs to generate multiphase signals. The proposed circuits have wide frequency tuning ranges and show good noise performances. The proposed six‐phase VCO can oscillate from 1.62 GHz to 3.45 GHz, which illustrates 72.2% tuning range. The phase noise of the proposed VCO is −97.5 dBc/Hz at 1 MHz offset frequency. The circuit figure of merit is −181.5 dBc/Hz. The post‐layout simulation results of the proposed six‐phase VCO are provided based on the TSMC 0.18 μm CMOS process. [ABSTRACT FROM AUTHOR]

This study presents a new wide-tunable, area-efficient and low-phase noise quadrature voltage-controlled oscillator(QVCO). Initially, a modified Colpitts voltage-controlled oscillator (VCO) is proposed in which all transistors are cross-connected in a self-biased scheme to increase negative resistance and facilitate the startup condition. Besides, instead of a passive inductor, a modified tunable active inducer (AI) is used in the proposed Colpitts VCO. Then a new AI-based QVCO is presented by the in-phase anti-phase coupling of two identical Colpitts VCOs. The core VCOs are coupled by the current source transistors of the AI and in this way, no extra coupling devices are used. The proposed AI-based QVCO is designed and simulated in TSMC 0. 1 8 μ m CMOS technology by Cadence. Post-layout simulation results show that the proposed QVCO occupies only 0. 0 2 4 mm 2 of chip area, and has a phase noise of −106.6 dBc/Hz at 1 MHz offset from the 0.7 GHz oscillation frequency. A wide frequency tuning range (FTR) of 68% (i.e., 0.68–1.4 GHz) is achieved by adjusting the tuning voltage of the active inductor (AI), and the total power consumption is 7.2 mW. Coarse and fine frequency tuning of the QVCO is available by changing the emulated inductors and varactors, respectively, that gives K vco of 1100 and 34 MHz/V, respectively. [ABSTRACT FROM AUTHOR]

In this paper, to analyze the tuning range (TR) of transistors, we introduced two streamlined modeling approaches that can precisely predict the extent and direction of the TR. The first approach, known as the average DC (Id) method, employed a simplified circuit model to dissect transistor characteristics, enabling us to understand the general trajectory of the TR. The second approach involved the transient current Id (tc) method, which offers a nuanced portrayal of the transistor's real‐world performance. By analyzing the current fluctuations within the transistor during transient states, its tuning capabilities could be more accurately ascertained. Further, this paper presents several designs for ultra‐wide‐tuning‐range complementary metal–oxide–semiconductor (CMOS) voltage‐controlled oscillators (VCOs) that employ a novel two‐mode current‐starved delay cell, featuring a tunable transistor‐based current source for coarse frequency adjustment operating in synergy with a varactor for precise tuning. Using the 65‐nm CMOS process, three prototype VCOs (Designs 2/3/4) based on the new cell and targeting different numbers of phases and performance were fabricated, thoroughly characterized, and compared with their traditional inverter‐based counterpart (Design 1). Design 1 featured an inverter‐based four‐phase structure, with an output frequency range of 3.14–9.82 GHz, i.e., a radio frequency (RF) TR of 103%, with phase noise (PN) ranging from 137.7 to 132.1 dBc/Hz at an offset of 100 MHz, figure of merit with tuning range and area (FoMTA) varying from 200.7 to 205.1 dBc/Hz, and area of 0.0036 mm2. In contrast, Designs 2/3/4, based on the new delay cell, featured 8/3/4 phases, with output frequencies in the ranges of 1.14–9.17, 1.26–16.53, and 1.15–18.32 GHz, respectively, resulting in increased RF TRs of 155.8%, 171.7% and 176.4%, as well as PN at an offset of 100 MHz in the ranges of 142.1–138, 130.5–131.3, and 131.9–129.6 dBc/Hz, respectively. This yielded better FoMTAs in the ranges of 201.2–209.9, 205.3–217.9, and 194.1–209.9 dBc/Hz, thus allowing the VCOs to maintain consistent performance across the frequency band and occupy comparable or smaller silicon areas of 0.00425, 0.000972, and 0.00348 mm2 in the same 65 nm technology. These designs showcase the versatility and efficiency of the two‐mode current‐starved delay architecture, which offers wide TRs, tiny areas, and competitive performance metrics for various applications in RF integrated circuits. [ABSTRACT FROM AUTHOR]

Optical frequency combs have revolutionized frequency metrology and spectroscopic measurements, enabling the most precise measurements of all physical quantities. However, precision frequency metrology heavily relies on mode‐locked laser combs, which are only directly available for a few selected near‐infrared wavelength ranges. Recently, a strong tendency emerged for combs in the mid‐infrared molecular fingerprint region. To this end, several methods for wavelength conversion have been proposed and demonstrated, which nevertheless cost a degradation of coherence properties. Here a first approach is presented toward measuring resulting phase noise fluctuations, exploiting the temporal resolution of the dispersive temporal interferometry (DTI) technique for experimentally unveiling the carrier‐envelope phase dynamics of a cw‐seeded femtosecond optical parametric amplifier (OPA). Particularly, it is experimentally demonstrated for the first time that unexpectedly low seed power levels suffice to exceed vacuum fluctuations by more than an order of magnitude, resulting in pulse‐to‐pulse phase fluctuations of 82 mrad at rather moderate cw seed levels of 8 mW. Additionally, a formula is provided that allows exact prediction of the experimentally observed noise levels. This study therefore provides new insight into the role of vacuum fluctuations in OPAs, which open up an avenue for coherent dual‐comb systems in the mid‐infrared and beyond. [ABSTRACT FROM AUTHOR]

Artificial-intelligence-generated content has driven explosive data traffic growth in data-center interconnects. Traditional direct detection solutions struggle with limited spectral efficiency and distance, prompting the shift to coherent optics for cost-sensitive short-reach links. One specific challenge is integrating low-cost lasers while overcoming severe phase noise on high-order modulation formats. Here, we propose a residual carrier modulation scheme for precise and efficient carrier frequency and phase recovery. The residual optical carrier can continuously track phase fluctuations without redundancy compared with discrete time-domain pilots, and address the digital-to-analog convertor resolution reduction issue of frequency-domain digital pilots. In proof-of-concept experiments, we transmit a net 1-Tb/s probabilistic-shaped 256-ary quadrature amplitude modulated (PS-256-QAM) signal using a 3 MHz distributed feedback (DFB) laser. Our scheme improves bitrate by 41% compared to conventional time-domain pilots, achieving a record laser linewidth sum and symbol duration product of 6.89 × 10−5. This approach supports MHz linewidth DFB lasers in low-cost coherent optical communications. The authors propose a residual carrier modulation scheme to overcome laser phase noise in coherent optical systems. The method improves bitrate and spectral efficiency by 41% using low-cost lasers, and showcase potential in cost-sensitive scenarios. [ABSTRACT FROM AUTHOR]

Context. The measurement of pulsar pulse times-of-arrival (ToAs) is a crucial step in detecting low-frequency gravitational waves. To determine ToAs, we can use template-matching to compare each observed pulse profile with a standard template. However, using different combinations of templates and template-matching methods (TMMs) without careful consideration can lead to inconsistent results. Aims. In pulsar timing array (PTA) experiments, distinct ToAs from the same observations can be obtained due to the use of diverse templates and TMMs. In other words, employing diverse approaches can yield different timing results and would thus have a significant impact on subsequent gravitational wave searches. In this paper we examine several commonly used combinations to analyze their effect on pulse ToAs. Methods. We evaluated the potential impact of template and TMM selection on 13 typical millisecond pulsars within the European PTA. We employed pulsar timing methods, specifically the root mean square and reduced chi-square (χ2r) of the residuals of the best timing solution, to assess the outcomes. Additionally, we evaluated the system-limited noise floor (SLNF) for each pulsar at various telescopes operating around 1.4 GHz using frequency-resolved templates. Results. Our findings suggest that utilizing data-derived and smoothed templates in conjunction with the Fourier-domain with Markov chain Monte Carlo TMM is generally the most effective approach, though there may be exceptions that require further attention. Furthermore, we determine that pulse phase jitter noise does not significantly limit the current precision of the European PTA's timing, as jitter levels derived from other studies are much lower than the SLNF. [ABSTRACT FROM AUTHOR]

For the time and frequency signals of Beidou satellites, a high-accuracy phase frequency detection technology based on phase group synchronization is proposed. Using the Beidou receiver and satellite signals as the frequency standard and the measured signals, respectively. The Beidou receiver and the satellite signals are sent to the phase coincidence detector of the different frequencies to generate a phase coincidence point pulse, which is sent to the different frequency phase detector as a control signal to generate the phase differences between the Beidou receiver and satellite signals, and then complete the high-accuracy phase synchronization between the Beidou receiver and satellite signals. Experimental results show that when the delay resolution reaches ps level, the phase synchronization accuracy of the system can reach 10 ps, which has the characteristics of small phase noise, low development cost, simple circuit structure, and high synchronization accuracy compared with the traditional phase synchronization technologies. Therefore, it would be widely used in satellite positioning, astrometry, precision navigation, aerospace, satellite launch, power transmission, communications, radar, and other high-tech fields. [ABSTRACT FROM AUTHOR]

Azimuth multi-channel synthetic aperture radar (SAR) has always been an important technical means to achieve high-resolution wide-swath (HRWS) SAR imaging. However, in the space-borne azimuth multi-channel SAR system, random phase noise will be produced during the operation of each channel receiver. The phase noise of each channel is superimposed on the SAR echo signal of the corresponding channel, which will cause the phase imbalance between the channels and lead to the generation of false targets. In view of the above problems, this paper proposes a random phase noise compensation method for space-borne azimuth multi-channel SAR. This method performs feature decomposition by calculating the covariance matrix of the echo signal and converts the random phase noise estimation into the optimal solution of the cost function. Considering that the phase noise in the receiver has frequency-dependent and time-varying characteristics, this method calculates the phase noise estimation value corresponding to each range-frequency point in the range direction and obtains the phase noise estimation value by expectation in the azimuth direction. The proposed random phase noise compensation method can suppress false targets well and make the radar present a well-focused SAR image. Finally, the usefulness of the suggested method is verified by simulation experiments. [ABSTRACT FROM AUTHOR]

Injection‐locked dividers feature ultrahigh operating frequency, low power consumption, and low phase noise, making them suitable for Q‐band phase‐locked loop. This paper presents a transformer‐based divide‐by‐4 injection locking frequency divider with a high third harmonic rejection buffer based on 40‐nm CMOS technology. Employing a fourth‐order transformer resonator enhances the third‐order harmonic amplitude, increasing the injection efficiency and expanding the locking range. The proposed high third harmonic rejection buffer using a source degeneration inductor can effectively suppress the output of the third harmonic caused by the resonator, ultimately yielding a clean fundamental frequency signal. Simulation results demonstrate that the proposed divide‐by‐4 injection‐locked frequency divider (ILFD) achieves a locking range of 10.2 GHz (from 40.3 to 50.5 GHz) with 0 dBm input signal. The core divide‐by‐4 ILFD circuit consumes 4.6 mW power with a 0.9 V supply and occupies an area of 0.026 mm2. [ABSTRACT FROM AUTHOR]

Non-Hermitian photonics, relaying on parity-time (PT) symmetry, have shown promise in achieving mode selection for optical or microwave single-mode oscillation. Typically, a PT-symmetric system is constructed using two coupled loops with identical geometry. This article utilizes the PT-symmetry property to select a single frequency mode in an optoelectronic oscillator (OEO). However, traditional OEO implementations often involve discrete components, limiting widespread adoption due to factors such as size, weight, power consumption, and cost. Our aim in this paper is to leverage integrated components within the OEO loop. The proposed structure incorporates an integrated micro-ring resonator (MRR) with a high-quality factor (Q-factor) that serves both as a modulator and a resonator. Additionally, we suggest employing an adjustable integrated power splitter utilizing a micro heater to balance the gain and loss of two mutually coupled OEO loops. In this configuration, two integrated photo detectors (PD) are also utilized. In this setup, the single-frequency mode can be easily identified by simultaneously utilizing the properties of PT-symmetry and an integrated high-Q-factor resonator, obviating the need for a narrowband microwave filter. By adjusting the center frequency of the microwave photonic filter (MPF), the frequency of the generated signal can be tuned over a wide range. For instance, setting the generated frequency of the microwave signal to 11.5 GHz results in a measured phase noise of − 76.5 dBc/Hz at a 10-kHz offset frequency, with a side mode suppression ratio (SMSR) of 40 dB. [ABSTRACT FROM AUTHOR]

A differential ring voltage‐controlled oscillator (DRVCO) is proposed in this paper as one of the critical blocks in communication systems. It consists of four stages of delay cells connected in a chain, creating a ring structure with auxiliary path interconnections. The oscillation frequency of the DRVCO can be controlled by adjusting the tuning voltage that controls the charging current. To achieve the desired performance for wireless applications, the Wu active inductor, which is a low‐noise and high‐quality factor active inductor, is employed in each delay cell for the first time. Using an active inductor provides a wide tuning range and also allows for proper phase noise and low power consumption. The proposed circuit is designed and simulated using standard 180‐nm CMOS technology with a 1.8‐V voltage source (VDD). The circuit is designed to achieve a tuning range of 2.15 GHz with a center frequency oscillation of 2.745 GHz, over the control voltage variation of 1.4 V (0 to 1.4 V). To achieve the desired performance, the circuit consumes an average power of 1.99 mW. It achieves a phase noise of − 91.2 dBc/Hz at 1 MHz offset frequency, indicating effective noise suppression. The figure of merit (FoM) for the circuit is − 156.9 dBc/Hz, representing its overall performance. The final layout of the circuit estimates an area of 0.00072 mm2. Various analyses, including Monte–Carlo simulations, PVT (process, voltage, temperature) variation analysis, and other relevant analyses, have been performed to ensure the reliable performance of the proposed circuit. [ABSTRACT FROM AUTHOR]

Cylindrical vector beams (CVBs) with unique spatial polarization states have attracted great interest in recent years. However, the generation of high-power CVBs faces a significant challenge due to the limited output power of a single laser. Here, we capitalize on the brightness enhancement offered by coherent beam combining (CBC) technique and propose an architecture for generating arbitrary CVBs based on a CBC system. The phase noise is effectively compensated using an all-fiber internal phase-locking technique. By designing the polarization direction of each beamlet in the laser array, the desired mode of CVB can be generated. This work could provide a reference for generating high-power CVBs. [ABSTRACT FROM AUTHOR]

This article proposed a technique for a low‐power and fast start‐up voltage‐controlled oscillator (VCO) for a high data rate 5 G New Radio (5G‐NR) application. The 5G‐NR high data rate signals require a fast start‐up VCO to accommodate the short pulse width. In this proposed work, a cross‐coupled pair (XCP) is integrated with a center‐tapped orthogonal symmetry inductor placed at the gates of the XCP, forming an inductive booster VCO (IBVCO). The inductive impedance at the gate of the XCP preserve the symmetry signal profile of the output voltage swing while alleviating the intrinsic parasitic capacitance effect and flicker noise effect of the transistor under the absence of the tail current source. The concept proves with the improvement on the phase noise performance and generating a fast start‐up without affecting the VCO bandwidth. The VCO also provides the enhancement of the output voltage swing under low power consumption. The IBVCO has been fabricated in 180 nm complementary metal oxide semiconductor technology and consumes a minimum area of only 0.7 mm2. The IBVCO achieved a 13% tuning range from 3.3 to 3.75 GHz bandwidth with a supply voltage, VDD of 0.7 V. The total power consumption is 1 mW with a corresponding phase noise of −122.60 dBc/Hz and a Figure of Merit (FoM) of 193.48 dBc/Hz at 3.52 GHz carrier center frequency at 1 MHz offset. The start‐up time of the VCO achieved is 5 ns. [ABSTRACT FROM AUTHOR]

Cosmic microwave background (CMB) experiments have deployed focal planes with O (10 4) transition edge sensor (TES) bolometers cooled to sub-Kelvin temperatures by multiplexing the readout of many TES channels onto a single pair of wires. Digital Frequency-domain Multiplexing (DfMux) is a multiplexing technique used in many CMB polarization experiments, such as the Simons Array, SPT-3 G, and EBEX. The DfMux system studied here uses LC filters with resonant frequencies ranging from 1.5 to 4.5 MHz connected to an array of TESs. Each detector has an amplitude-modulated carrier tone at the resonant frequency of its accompanying LC resonator. The signal is recovered via quadrature demodulation where the in-phase (I) component of the demodulated current is in phase with the complex admittance of the circuit and the quadrature (Q) component is orthogonal to I. Observed excess current noise in the Q component is consistent with fluctuations in the resonant frequency. This noise has been shown to be non-orthogonal to the phase of the detector's responsivity. We present a detailed analysis of the phase of responsivity of the TES and noise sources in our DfMux readout system. Further, we investigate how modifications to the TES operating resistance and bias frequency can affect the phase of noise relative to the phase of the detector responsivity, using data from Simons Array to evaluate our predictions. We find that both the phase of responsivity and phase of noise are functions of the two tuning parameters, which can be purposefully selected to maximize signal-to-noise (SNR) ratio. [ABSTRACT FROM AUTHOR]

In recent years, absolute gravity comparison experiments between cold atomic gravimeter and traditional gravimeter have been carried out by combining cold atomic gravimeter with stable platform. Due to the working characteristics of the stable platform, the tilt angle of the cold atomic gravimeter will change slightly in the process of dynamic measurement, and the measurement noise will be introduced. In order to improve the accuracy of dynamic measurement, this paper first analyzes the trajectory of the mirror and atom in the atomic gravimeter combined with carrier motion information, obtains the phase expression of the atomic interferometer using the translation and rotation matrix, evaluates the main terms of the gravity deviation using the 20-min navigation data on the ship in the South China Sea, and simplifies the higher-order small-terms in the main terms to deduce the simplified form of the gravity deviation. Then, the Fourier transform is used to transform the simplified expression into the power spectrum expression of phase noise, the corresponding noise sensitivity function is used in the form of trigonometric. The 20-min data is divided into 10 intervals, the root-mean-square (RMS) value of the overall gravity deviation is 1.5–3 mGal using the power spectrum of the platform angle, angular velocity and carrier acceleration in each interval. The variation fluctuation of the RMS value is consistent with the fluctuation of solving the gravity deviation through the trajectory. The conclusion provides the calculation method of gravity noise caused by dynamic tilt change and horizontal acceleration, and also provides the basis for platform design. [ABSTRACT FROM AUTHOR]

Robustness against Electronic Warfare/Electronic Defence attacks represents an important advantage of Noise Radar Technology (NRT). An evaluation of the related Low Probability of Detection (LPD) and of Intercept (LPI) is presented for Continuous Emission Noise Radar (CE‐NR) waveforms with different operational parameters, that is, "tailored", and with various "degrees of randomness". In this frame, three different noise radar waveforms, a phase Noise (APCN) and two "tailored" noise waveforms (FMeth and COSPAR), are compared by time–frequency analysis. Using a correlator (i.e. a two antennas) receiver, assuming a complete knowledge of the band (B) and duration (T) of the coherent emission of these waveforms, it will be shown that the LPD features of a CE‐NR do not significantly differ from those of any CE radar transmitting deterministic waveforms. However, in real operations, B and T are unknown; hence, assuming an instantaneous bandwidth estimation will show that the duration T can be estimated only for some specific "tailored" waveforms (of course, not to be operationally used). The effect of "tailoring" is analysed with prospects for future work. Finally, some limitations in the classification of these radar signals are analysed. [ABSTRACT FROM AUTHOR]

Research on two-dimensional material-based phototransistors has recently become a topic of great interest. However, the high number of design features, which impact the performance of these devices, and the multi-physical nature of the device operation make the accurate analysis of these devices a challenge. Here, we present a simple yet effective numerical framework to overcome this challenge. The one-dimensional framework is constructed on the drift-diffusion equations, Poisson's equation, and wave propagation in multi-layered medium formalism. We apply this framework to study phototransistors made from monolayer molybdenum disulfide ( MoS 2 ) placed on top of a back-gated silicon-oxide-coated silicon substrate. Numerical results, which show good agreement with the experimental results found in the literature, emphasize the necessity of including the inhomogeneous background for accurately calculating device metrics such as quantum efficiency and bandwidth. For the first time in literature, we calculate the phase noise of these phototransistors, which is a crucial performance metric for many applications where precise timing and synchronization are critical. We determine that applying a low drain-to-source voltage is the key requirement for low phase noise. [ABSTRACT FROM AUTHOR]

In a linear and quadratic optomechanical system with optical parametric amplifier's (OPA) phase noise, we conduct a study on normal-mode splitting, sideband cooling and force sensitivity. The system encompasses an optical cavity, a mechanical membrane and a degenerate OPA. When there is OPA's pump phase noise, normal-mode splitting still occurs and displays more complex splitting compared to scenarios without phase noise. Specifically, for increasing quadratic coupling, the left peak shrinks steadily until it vanishes, while the right peak increases to a larger value. Moreover, both the nonlinear gain of OPA and the quadratic coupling parameter play key roles in cooling the mechanical membrane in the presence of certain phase noise. Minimal phase noise and optimized values of the nonlinear gain of OPA and the quadratic coupling are essential for achieving enhanced cooling. Furthermore, in the presence of OPA's phase noise, when the value of quadratic coupling is negative, the standard quantum limit is beaten. Higher negative values of quadratic coupling prove beneficial in achieving more stable force sensitivity. We believe that in the realm of quantum optomechanics, this scheme may have viable applications in quantum manipulation and precision measurement. [ABSTRACT FROM AUTHOR]

In this paper, an optoelectronic oscillator (OEO) with ultra-low phase noise and high stability based on the injection-locked and phase-locked loop is proposed. In theory, the injection-locked frequency range of the injection signal is studied based on the phase dynamics equation, and the phase noise performance of the injection-locked OEO is analyzed. The role of the phase-locked loop on the frequency stability of the OEO is analyzed based on the phase-locked loop transfer function. In addition, this paper builds an injection-locked OEO based on a phase-locked loop. The injection-locked signal is the high-frequency output of the multiplication crystal oscillator (MCO). At the same time, this MCO synchronously outputs a low-frequency signal, which is used as the reference signal of the phase-locked loop. The experimental results show that the proposed OEO output frequency is 10 GHz, and the phase noise is −89.25 dBc/Hz@100 Hz, −121.71 dBc/Hz@1 kHz, and −145.39 dBc/Hz@10 kHz; the side-mode suppression ratio is 80 dB; the frequency stability is 2.06 × 10 − 11 @1 s, 9.03 × 10 − 11 @10 s, 1.03 × 10 − 10 @100 s, and 3.03 × 10 − 10 @1000 s. Consistent with the theoretical analysis results, the solution takes into account the frequency stability, side-mode suppression ratio, and phase noise performance. The simple structure is more advantageous in practical applications. [ABSTRACT FROM AUTHOR]

A microwave photonic frequency multiplier with low phase noise based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. In this scheme, a dual-parallel Mach–Zehnder modulator (DPMZM) is employed to generate the third-harmonic frequency of the input radio frequency (RF) signal, while the oscillation frequency of the OEO is also three times the RF signal frequency. By adjusting the bias voltages of different arms in the DPMZM, a triple-frequency signal with a high side-mode suppression ratio of 64.8 dB can be obtained. The experimental results indicate that the output of the frequency-multiplier has a better single-sideband phase noise value, for instance, −126 dBc/Hz@10 kHz at 20.019 GHz. It has improvements of 34 dB and 43.5 dB compared with the input RF signal and the simulated electrical frequency tripler module, respectively. [ABSTRACT FROM AUTHOR]

High-precision time–frequency is widely used in time measurement, satellite navigation, scientific research, and other fields. With the rapid development of optical clock technology, the fractional frequency instability and uncertainty of optical clock have reached 10−18 orders of magnitude, which is expected to contribute to generating the International Atomic Time and may even be used to redefine the "second" in the future. Therefore, the long-distance transfer of time–frequency signals between optical atomic clocks is of great significance. Free-space optical frequency transfer technology is one of the important technologies for solving the space-based optical clock comparison because of its high transfer precision and easy networking characteristics. In order to solve the long-distance space-based optical clock comparison, this paper investigates a free-space active phase noise compensation method using an Acousto-Optic Modulator (AOM), based on the traditional optical fiber phase noise compensation scheme. This new method is more flexible and scalable than the optical fiber time–frequency transfer technology. The optical frequency transfer over a 64 m free-space link is demonstrated. The fractional frequency transfer instability during free running is 9.50 × 10−16 at 1 s, and 4.44 × 10−16 at 2000 s, and the fractional frequency instability after compensation is 7.10 × 10−17 at 1 s, 3.07 × 10−19 at 2000 s, which is about 1–3 orders of magnitude better than that in free running, and provides a feasible scheme for space-based optical clock comparison. [ABSTRACT FROM AUTHOR]

PLLs with small areas, low power consumption, and low jitter are crucial for mobile applications. Hence, achieving a balance between the area, power consumption, and noise of a PLL is a significant issue. In this work, a compact, low-power, and low-jitter fractional-N PLL using Ring-VCO is introduced. In order to reduce area and power consumption, a single-ended Ring-VCO is implemented. Additionally, novel resistance matrixes are proposed to decrease phase noise. The resistor matrix creates 13 frequency tuning curves with close VCO gain and different initial frequencies, reducing the VCO gain and thus the overall noise while maintaining high tuning linearity. The proposed PLL is fabricated based on 12 nm FinFET technology with a 0.078 mm2 area. It achieves a 2.702 ps RMS jitter at 5.76 GHz while consuming 6.4 mW. Moreover, it maintains a low power consumption and a low RMS jitter across the entire frequency range. [ABSTRACT FROM AUTHOR]

In this article, a qualitative work is carried out based on research of uniform PRF signal for phase noise analysis and accuracy parameter for RF sensor design. Presence of large clutter level in target return needs in-depth analysis of phase noise impact in clutter cancellation and importance of PRF selection in RF sensor processed SNR or accuracy. Detailed investigation of phase noise parameter in pulsed RF secnsor is examined out for target identification and tracking purpose. Critical aspects of phase noise in multiple PRF mode has been analyzed and Matlab simulations are carried out to support theoretical aspects of noise effects at particular offset. Impact of phase noise in clutter cancellation for uniform PRF waveform and multiple uniform PRF waveforms is evaluated in terms of SNR, sensor accuracy and allied limitations. Thus, outcomes can be utilized to unique analysis of PRF selection and phase noise together for RF sensor accuracy. Present work findings and results have been validated using simulation environment. This research outcomes offer great importance in design of highly accurate RF sensor. [ABSTRACT FROM AUTHOR]

Abstract The authors deal with the problem of the design and manufacture of a high‐resolution FMCW radar for drone detection and classification. The difficulties of the problem are discrete clutter reduction and spurious phase noise mitigation. The discrete clutter is due to the reflected signals from land vehicles, birds etc., while the spurious phase noise is inherent in the radar signal due to the phase‐locked loop component and leakage between the transmitting and receiving paths. Both spurious phase noise and clutter will increase the system noise level and hence reduce the probability of detection of small targets such as drones and induce false alarms on the radar screen. In order to reduce discrete clutter, the authors propose a method to separate a drone from discrete clutter based on the design of the radar system parameters for a drone and its propeller detection, target's Doppler dispersion and moving characteristics. For spur mitigation, a method that focuses on the design of the isolation coefficient between transmitting and receiving paths to decrease the power of spurs below the minimum power requirement at the input of the analogue‐to‐digital converter is introduced. The results were applied by the authors to the development and manufacture of a radar with the given specifications for drone detection and classification. Different laboratory and field tests show that the spurs are mitigated and the drones are separated from discrete clutter with a range and accuracy better than the one recently published.

White blood cells (WBCs) are one of the most significant parts of the human immune system, and they play a crucial role in diagnosing the characteristics of pathologists and blood-related diseases. The characteristics of WBCs are well-defined based on the morphological behavior of their nuclei, and the number and types of WBCs can often determine the presence of diseases or illnesses. Generally, there are different types of WBCs, and the accurate classification of WBCs helps in proper diagnosis and treatment. Although various classification models were developed in the past, they face issues like less classification accuracy, high error rate, and large execution. Hence, a novel classification strategy named the African Buffalo-based Convolutional Neural Model (ABCNM) is proposed to classify the types of WBCs accurately. The proposed strategy commences with collecting WBC sample databases, which are preprocessed and trained into the system for classification. The preprocessing phase removes the noises and training flaws, which helps improve the dataset's quality and consistency. Further, feature extraction is performed to segment the WBCs, and African Buffalo fitness is updated in the classification layer for the correct classification of WBCs. The proposed framework is modeled in Python, and the experimental analysis depicts that it achieved 99.12% accuracy, 98.16% precision, 99% sensitivity, 99.04% specificity, and 99.02% f-measure. Furthermore, a comparative assessment with the existing techniques validated that the proposed strategy obtained better performances than the conventional models. [ABSTRACT FROM AUTHOR]

The estimation of the parameters of a sinusoidal signal is of paramount importance in various applications in the fields of sensors, signal processing, parameter estimation, and device characterization, among others. The presence, in the measurement system, of non-ideal phenomena such as additive noise in the signals, phase noise in the stimulus generation, jitter in the sampling system, frequency error in the experimental setup, among others, leads to increased uncertainty and bias in the estimated quantities obtained by least squares methods and those derived from them. Therefore, from a metrological point of view, it is important to be able to theoretically predict and quantify those uncertainties in order to properly design the measurement system and its parameters, such as the number of samples to acquire or the stimulus signal amplitude to use to minimize the uncertainty in the estimated values. Previous works have shown that the presence of these non-ideal phenomena leads to increased uncertainty and bias in the estimation of the sinewave amplitude. The present work complements this knowledge by focusing specifically on the effect of phase noise and sampling jitter in the bias of the initial phase estimation of a sinusoidal signal of known frequency (three-parameter sine fitting procedure). A theoretical derivation of the bias of initial phase estimation that takes into consideration the presence of phase noise in the sinewave is presented. Since a Taylor series approximation was used where only the first term was retained, it was necessary to validate the analytical derivations with numerical simulations using a Monte Carlo type of procedure. This process was applied to different conditions regarding the phase noise standard deviation, initial phase value, and number of samples. It is concluded that, in most scenarios, initial phase estimation using sine fitting is unbiased in the presence of phase noise or jitter. It is shown, however, that in cases of extremely high phase noise standard deviation and a very low number of samples, a bias occurs. [ABSTRACT FROM AUTHOR]

Coherent light beams play an important role in the development of opto‐electronic microwave and terahertz technologies, serving as a source for generating RF carrier signals with very high quality. The authors explore in this work an approach to enhance the coherence between two incoherent lasers so as to provide coherent light beams, and proof‐of‐concept demonstrates a terahertz signal generation with low phase noise. Based on the proposed passive phase compensation technique, the phase noise between two independent lasers can be well suppressed and the carrier to noise ratio in the terahertz regime remains high. In the experiment, the beating phase noise between two independent lasers is reduced from −60.68 dBc/Hz@10kHz to −90.05 dBc/Hz@10kHz at about 280 GHz, which is promisingly applicable in the terahertz photonics community. [ABSTRACT FROM AUTHOR]

Microwave impedance microscopy (MIM) is an emerging scanning probe technique for nanoscale complex permittivity mapping and has made significant impacts in diverse fields. To date, the most significant hurdles that limit its widespread use are the requirements of specialized microwave probes and high-precision cancellation circuits. Here, we show that forgoing both elements not only is feasible but also enhances performance. Using monolithic silicon cantilever probes and a cancellation-free architecture, we demonstrate Johnson-noise-limited, drift-free MIM operation with 15 nm spatial resolution, minimal topography crosstalk, and an unprecedented sensitivity of 0.26 zF/√Hz. We accomplish this by taking advantage of the high mechanical resonant frequency and spatial resolution of silicon probes, the inherent common-mode phase noise rejection of self-referenced homodyne detection, and the exceptional stability of the streamlined architecture. Our approach makes MIM drastically more accessible and paves the way for advanced operation modes as well as integration with complementary techniques. The authors introduce a new approach to microwave impedance microscopy, eliminating once-indispensable specialized probes and cancellation circuits. Using monolithic silicon probes and a streamlined architecture, they achieve 0.26 zF/√Hz sensitivity and 15 nm resolution with drift-free operation. [ABSTRACT FROM AUTHOR]

Optical resonators are indispensable tools in optical metrology that usually benefit from an evacuated and highly-isolated environment to achieve peak performance. Even in the more sophisticated design of Fabry-Perot (FP) cavities, the material choice limits the achievable quality factors. For this reason, monolithic resonators are emerging as promising alternative to traditional designs, but their design is still at preliminary stage and far from being optimized. Here, we demonstrate a monolithic FP resonator with 4.5 cm3 volume and 2 × 105 finesse. In the ambient environment, we achieve 18 Hz integrated laser linewidth and 7 × 10−14 frequency stability measured from 0.08 s to 0.3 s averaging time, the highest spectral purity and stability demonstrated to date in the context of monolithic reference resonators. By locking two separate lasers to distinct modes of the same resonator, a 96 GHz microwave signals is generated with phase noise -100 dBc/Hz at 10 kHz frequency offset, achieving orders of magnitude improvement in the approach of photonic heterodyne synthesis. The compact monolithic FP resonator is promising for applications in spectrally-pure, high-frequency microwave photonic references as well as optical clocks and other metrological devices. ©2024. All rights reserved. Optical resonators are essential tools for high precision metrology and applications where the spectral purity is highly demanded. Here, the authors demonstrate a monolithic resonator made of fused silica to support 18 Hz integrated laser linewidth in the ambient environment, and W-band microwave generation with low phase noise of -100 dBc/Hz at 10 kHz frequency offset. [ABSTRACT FROM AUTHOR]

The present article proposes a novel method to reduce phase noise in a PLL based X-Band source consisting of oscillating and non-oscillating components for the use in Pulse Doppler radar. It also provides phase noise performance stabilization under random vibration. The method consists of improved electrical design and PCB layout, noise filtering technique and passive isolation scheme to suppress vibration-induced noise. Acceleration sensitivity is an important requirement for radars and sensors mounted in unmanned aerial vehicles, aircrafts, missiles and other dynamic platforms. These systems provide superior performance when subjected to severe environmental condition. However, mechanical vibration and acceleration can introduce physical deformation that thereby degrades the frequency source generated signal phase noise. It effects the complete radar system that depends on frequency source performance. The development and testing of a stable X-Band source at 10.64 GHz using indirect method has been carried out which proved that the phase noise is stable both in steady state and under random vibration of 7g magnitude. The study of critical design aspects of test fixture, test object mounting arrangement, investigation on vibration response and performance stabilization along with description of test setup and measurement procedure has been reported. An improvement of around 35-40 dB in phase noise is achieved at close-in offset frequencies. Few challenges and suggestions for the accurate measurement of random vibration testing for frequency sources have also been mentioned. [ABSTRACT FROM AUTHOR]

Time-series SAR interferometry (InSAR) combining permanent scatterer and distributed scatterer (DS), has been strongly developed in subsidence monitoring. It is known that the Component extrAction and sElection SAR (CAESAR) is a recently presented approach of selecting and filtering scattering mechanisms for DS. This article proposes an improved CAESAR algorithm in InSAR processing. Phase optimization is performed by eigenvalue decomposition and principal component analysis of the coherence matrix that constructed based on the identified homogeneous pixels. In addition, only the interferometric phases with low noise are used to calculate the goodness-of-fit value. The improved method has been tested for subsidence monitoring over a nonurban area located in Xiongxian, China using 25 Sentinel-1A images. The results show that the improved method can provide the high spatial density of deformation measurements with accuracy ensured. Noticeable land subsidence is revealed widely within the north of Xiongxian county, particularly in Daying, Mijiawun and Beishakou towns. [ABSTRACT FROM AUTHOR]

This paper proposes a phase noise model of ISF based on PSS+PXF to predict the phase noise of the oscillator. Compared with the traditional Lazavi model, the model takes into account the nonlinear time-varying characteristics of the oscillator, so it is more accurate. The effectiveness of the model is verified through simulation. The phase noise model precision of the ISF based on PSS+PXF is more than 200%higher than that of the traditional Razavi model. [ABSTRACT FROM AUTHOR]

Second generation quantum technologies aim to outperform classical alternatives by utilizing engineered quantum systems. Maintaining the coherence required to enable any quantum advantage requires detailed knowledge and control over the noise that the hosting system is subjected to. Characterizing noise processes via their power spectral density is routinely done throughout science and technology and can be a demanding task. Determining the phase noise power spectrum in leading quantum technology platforms, for example, can be either outside the reach of many phase noise analyzers or prohibitively expensive. In this work, we present and characterize a low-complexity, low-cost optical phase noise analyzer based on the short-delay optical self-heterodyne measurements for quantum technology applications. Using this setup, we compare two ≈1 Hz linewidth ultra-stable oscillators near 729 nm. Their measurements are used as a baseline to determine and discuss the noise floor achieved in this measurement apparatus with a focus on limitations and their tradeoffs. The achieved noise floor in this all-stock-component implementation of an optical phase noise analyzer compares favorably with commercial offerings. This setup can be used particularly without a more stable reference or operational quantum system as a sensor as would be the case for many component manufacturers. [ABSTRACT FROM AUTHOR]

Narrow-linewidth lasers mainly depend on the development of advanced laser linewidth measurement methods for related technological progress as key devices in satellite laser communications, precision measurements, ultra-high-speed optical communications, and other fields. This manuscript provides a theoretical analysis of linewidth characterization methods based on the beat frequency power spectrum and laser phase noise calculations, and elaborates on existing research of measurement technologies. In addition, to address the technical challenges of complex measurement systems that commonly rely on long optical fibers and significant phase noise jitter in the existing research, a short-delay self-heterodyne method based on coherent envelope spectrum demodulation was discussed in depth to reduce the phase jitter caused by 1/f noise. We assessed the performance parameters and testing conditions of different lasers, as well as the corresponding linewidth characterization methods, and analyzed the measurement accuracy and error sources of various methods. [ABSTRACT FROM AUTHOR]

By integrating sensing capability into wireless communication, wireless sensing technology has become a promising contactless and non-line-of-sight sensing paradigm to explore the dynamic characteristics of channel state information (CSI) for recognizing human behaviors. In this paper, we develop an effective device-free human gesture recognition (HGR) system based on WiFi wireless sensing technology in which the complementary CSI amplitude and phase of communication link are jointly exploited. To improve the quality of collected CSI, a linear transform-based data processing method is first used to eliminate the phase offset and noise and to reduce the impact of multi-path effects. Then, six different time and frequency domain features are chosen for both amplitude and phase, including the mean, variance, root mean square, interquartile range, energy entropy and power spectral entropy, and a feature selection algorithm to remove irrelevant and redundant features is proposed based on filtering and principal component analysis methods, resulting in the construction of a feature subspace to distinguish different gestures. On this basis, a support vector machine-based stacking algorithm is proposed for gesture classification based on the selected and complementary amplitude and phase features. Lastly, we conduct experiments under a practical scenario with one transmitter and receiver. The results demonstrate that the average accuracy of the proposed HGR system is 98.3% and that the F1-score is over 97%. [ABSTRACT FROM AUTHOR]

In this paper, we present a data-aided feedback technique based on the recursive least squares (RLS) algorithm to synchronize the local oscillator with the remote carrier by jointly estimating the carrier frequency offset (CFO) and phase noise (PN), even for large CFO ranges with better laser linewidth tolerance. The CFO and PN are modeled together by a linear regression model, and the filter coefficient vector is recursively learned using the RLS algorithm. Numerical simulation results on a polarization division multiplexed 16QAM, 224 Gbps data rate system with multiple spans demonstrate a significant improvement in Q-factor over other widely used techniques such as blind phase search and fourth-order periodogram maximization. Furthermore, the proposed technique has been shown to achieve synchronization of the carrier at a CFO as high as 10 GHz and exhibits a laser linewidth tolerance as high as 1.45 MHz in the low CFO range. Analysis of our proposed technique shows that computational complexity is much less compared to other widely used techniques. [ABSTRACT FROM AUTHOR]

In high-frequency electronics, optimizing RF oscillators performance is essential, especially as applications reach into wide frequency bands. This article describes proposed clock generators for UWB sensor systems based on oscillators with dielectric resonator (DRO). Evaluation boards with different sizes of microstrip conductors were developed and tested, based on which new versions of boards were created. Improvements were made to integrate the DRO into a shielded box to ensure minimal external interference. The final designs demonstrated stable operation with low phase noise λ (1 MHz) = -108.805 dBc at fc = 21.732 GHz, sufficient power (3.65 dBm) and low power consumption(56 mW). [ABSTRACT FROM AUTHOR]