Frequency Pushing Research Articles

Frequency pushing and pulling in semiconductor lasers subject to optical frequency comb injection

We theoretically investigate the frequency shift of a free-running semiconductor laser when optically injected by an optical frequency comb. By numerical integration of the laser rate equations, we have identified two types of frequency shifts, frequency pulling, and frequency pushing. The free-running slave laser seems to switch between pulling and pushing in a regular manner. We have systematically determined the dependence of these shifts on comb parameters, including comb spacing and number of lines. We have found that the occurring frequency pushing seems to be almost independent of comb signals and comb spacing, while in contrast, the frequency pulling shows weak dependence on comb signals but largely affected by comb spacing. We have also shown that carrier density dynamic is the origine of these phenomena.

Frequency pushing enhanced by an exceptional point in an atom–cavity coupled system

We observed the frequency pushing of the cavity resonance as a result of the coupling of the cavity field with the ground state 138Ba in a high-Q cavity. A weak probe laser propagated along the axis of a Fabry–Pérot cavity while ground-state barium atoms traversed the cavity mode perpendicularly. By operating the atom–cavity composite in the vicinity of an exceptional point, we could observe a greatly enhanced frequency shift of the cavity transmission peak, which was pushed away from the atomic resonance, resulting in up to 41 ± 7 kHz frequency shift per atom from the empty cavity resonance. We analyzed our results by using the Maxwell–Schrödinger equation and obtained good agreement with the measurements.

Dynamic characterization of supercritical natural circulation loop under periodic excitation

Characterization of supercritical natural circulation loop under the influence of periodic power profile has not been explored in open literature, despite the promise of producing intriguing dynamics. Present study employs a one-dimensional numerical model to explore the transients on imposing a sinusoidal excitation on the heater power. The resultant dynamics are found to be strongly correlated with the heat transfer regime. The time period of excitation plays a more dominating role compared to the amplitude in deciding the characteristics. System attains dynamic steady-state and persists with a periodic profile at both low and high power levels. But introduction of natural frequency emanates into flow reversal at power levels within the transition regime. Chaotic oscillations can be identified for an intermediate band of imposed frequency, transforming to bidirectional pulsing at higher time periods. Frequency locking within the chaotic zone and frequency pushing for double-periodic nature is also identified, and the appearance of chaos is substantiated using the Poincaré map.

Influence of Power Supply Ripple on Injection Locking of Magnetron with Frequency Pushing Effect

The influence of anode voltage ripple on injection locking of a magnetron with frequency pushing effect has been studied systematically. Theoretical analysis shows that, when power supply ripple and injection ratio are constant, frequency pushing effect will increase the magnetron’s locking bandwidth. Meanwhile, the locking bandwidth decreases with the increase of power supply ripple. Thus, to achieve injection locking, both power supply ripple and frequency pushing effect must be considered. The experiment results show that at injection ratio μ of 0.003, frequency pushing effect at 0.5, and power supply ripple increases from 0% to 1% and 2.5%, the locking bandwidth of magnetron decreases by 0.32 MHz, 2.12 MHz. With the amplitude of ripple increasing, the spectrum after injection locking deteriorates, and output amplitude reduces, which verifies the theoretical analysis. Considering anode voltage ripple and frequency pushing effect, the research results contribute to the realization of high-quality output of injection locked magnetrons.

Power Combining of DualX-Band Coaxial Magnetrons Based on Peer-to-Peer Locking

A system for the power combining of dual X-band coaxial magnetrons-based on the peer-to-peer locking is presented in this article. The locking condition of peer-to-peer locking was derived and proposed, in which the frequency pushing effect was taken into account. The frequency pushing parameter of X-band coaxial magnetron was measured by an injection locking experiment. Dual X-band coaxial magnetrons with similar operation characteristics were employed and driven by single modulator to synchronize the pulse generation in the power combining system based on peer-to-peer locking. As the prediction of theoretical derivation, the locking phenomenon emerged with a locked frequency of 9304.41 MHz when the free running frequency of one magnetron was fixed as 9304 MHz. A combined power of 3.09 MW for 3.5 μs pulsewidth with the total power efficiency of 83.5% was achieved in the experiment, which was approximately 1.5 times the maximum peak output power of commercial X-band coaxial magnetron. Due to the measured phase jitter of ±8° caused by the anode current ripple and frequency fluctuation of the magnetrons, the combined power jitter was estimated as ±0.5%, which was acceptable for the system.

Investigation of Dielectric Resonator Oscillator Using High-Electron Mobility Transistor at 26GHz for Space Applications

An oscillator is a vital component as the energy source in microwave telecommunication system. Microwave oscillators designed using Gunn diode have poor DC to RF efficiency. IMPact Ionization Avalanche Transit-Time diode (IMPATT) oscillators have the drawback of poor noise performance. The transistorized oscillators have a limitation to the maximum oscillation frequency which means that they cannot be used for oscillators designed for high frequencies. To design negative series feedback Dielectric Resonator Oscillator (DRO), the resonant unit uses a dielectric resonator (DR) since it is small in size, light in weight, has high-Quality ([Formula: see text]) factor, better stability and also it is inexpensive. It has the benefits of low-phase noise, low cost, miniaturization, high stability, applicable for devices designed at high frequencies and had already been widely applied, so the research on microwave dielectric oscillator has also been one of the focus of today’s microwave integrated circuits. DRO is widely used in electronic warfare, missile, radar and communication systems. The DRO incorporates High-Electron Mobility Transistor (HEMT) as an active device since it offers higher power-added efficiency combined with excellent low-noise figures and performance. The entire circuit of DRO using HEMT at 26[Formula: see text]GHz is designed using Agilent Advanced Design System (ADS) software. In this, DRO different measurements of parameters are done such as output power which is typically [Formula: see text][Formula: see text]dBm for 26[Formula: see text]GHz DRO, phase noise at 10[Formula: see text]kHz offset for 26[Formula: see text]GHz DRO it is 80[Formula: see text]dBc/Hz. The frequency pushing and frequency pulling for 26[Formula: see text]GHz DRO its typical values are 30[Formula: see text]kHz/V and 1[Formula: see text]MHz, respectively.

(Invited) Optoelectronic and Dielectric Properties of Organic Cation Tin-Based Perovskite Solar Cells

Tin iodide perovskite (ASnI3) is one of the most feasible, less toxic alternatives to lead halide perovskite (APbX3), owing to its readily formed three-dimensional (D) structure and more suited bandgap (1.2–1.4 eV) of the solar cell application than APbX3 (1.5–2.3 eV). Regardless of the skyrocketing boost in Pb perovskite solar cells throughout this decade, Sn-based counterparts have remained constrained because of the intrinsically unstable Sn2+ that is easily oxidized to Sn4+. The resultant p-doping causes electron trapping and a shorting of the diode circuit, which is partly mitigated by SnF2 addition. Nevertheless, the power conversion efficiency (PCE) values of MASnI3 (MA: methylammonium cation) based on a normal cell structure (mesoporous TiO2/active layer/hole transport layer: HTL) have been suppressed due to the p-doping and low film quality. Notably, progress in an inverted cell structure (HTL/active layer/electron transport layer: ETL) has been reported for FASnI3 (FA: formamidinium cation) mixed with either MA, PEA (phenylethylamine cation), EDA (ethylenediammonium dication), or GA (guanidium cation). In addition to this A-site cation mixing strategy associated with 2D/3D perovskites, the use of {en} (ethylenediammonium), SnX2-(pyrazine, trimethylamine, or solvent) complexes, hot anti-solvent treatment (HAT), poly(vinyl alcohol) (PVA) addition, and GeI2 dopingreportedly showed improvement in PCEs. Thus, the updated PCE in the forefront of the Sn perovskite solar cell is ~9–10%, which is enabled by MA/FA mixing, FA/PEA mixing, GA/FA mixing, as well as the addition of 4-fuorobenzohydrazide (FBH), 2-cyano-3-[5-[4-(diphenylamino)phenyl]-2-thienyl]-propenoic acid (CDTA), or passivation with ethylenediamine (edamine). Although the mixing of A-site cations, along with additives, has been found to smooth the film surface, decrease the Sn4+ impurities, and tune the valence band maximum (VBM), their effects on charge carrier dynamics and morphological changes are the subject of ongoing debate.We characterized the solar cells composed of ternary A-site cation-mixed Sn perovskite: ASnI3 [A = (GAxFA1–x)0.9PEA0.1, the ratios are the precursor stoichiometry] by changing the GA content (x = 0–1) and investigated their charge carrier dynamics, surface morphologies, and energetics.[1] The inclusion of 10 mol% PEA was found necessary for performing these evaluations over a wide range of GA:FA ratios. Electrode-less, time-resolved microwave conductivity (TRMC) measurements[2] were applied to a pristine ASnI3 film, double layers of HTL/ASnI3 and ASnI3/ETL, as well as a triple layer of HTL/ASnI3/ETL, where PEDOT:PSS and thermally evaporated fullerene (C60) were used as the HTL and ETL, respectively. These comparative samples with different GA contents discerned the contributions of hole and electron mobilities in the TRMC transients. Notably, the change in electron mobilities corresponded to the PCE dependence on the GA content, highlighting the pivotal role of electron mobility in solar cell performance. We further examined the atomic force microscopy (AFM) surface images, VBM measured by photoelectron spectroscopy (PYS), and crystalline features measured by X-ray diffraction (XRD), which supports the dramatic change of charge carrier mobility and lifetime.On one hand, the dielectric properties of organic-inorganic hybrid perovskite materials have remained poorly understood, despite probably influencing delayed charge recombination and device capacitance. We characterize the unprecedented dielectric behavior of MHPs comprising methylammonium cations, Pb/Sn as metals, and Br/I as halides using TRMC measurements.[3] At specific compositions, the above MHPs exhibit negative real and positive imaginary photoconductivities, the polarities of which are opposite to those observed for conventional photogenerated charge carriers. Comparing the observed TRMC kinetics with that of inorganic perovskites (SrTiO3 and BaTiO3) and characterizing its dependence on temperature, frequency and near-infrared second push pulse, we conclude that the above behavior is due to the trapping of polaronic holes/electrons by oriented dipoles of organic cations, which opens a hitherto unexplored route to the dynamical control of dielectric permittivity by photoirradiation.Reference Nakanishi, R. Nishikubo, A. Wakamiya, A. Saeki, J. Phys. Chem. Lett. 11 (2020) 4043.Saeki, A. Polym. J. 52 (2020) 1307.Yamada, R. Nishikubo, H. Oga, Y. Ogomi, S. Hayase, S. Kanno, Y. Imamura, M. Hada, A. Saeki, ACS Photonics 5 (2018) 3189.

A 0.2-V Three-Winding Transformer-Based DCO in 16-nm FinFET CMOS

In this brief, we introduce a 3.2–4 GHz three-winding transformer-based class-F digitally controlled oscillator (DCO) with a DC-DC booster for energy harvesting applications. A $\pi $ -model is adopted for this multi-turn transformer to analyze its impedance transformation and overall loop gain. The trifilar coil generates large passive voltage loop gain, allowing the DCO supply voltage of 0.2 V to be even lower than the threshold voltage of transistors without any performance degradation. Due to the gate/drain isolation as well as smaller voltage-dependent capacitance in advanced FinFET technology, this brief achieves very low supply frequency pushing of 38 MHz/V. The switched capacitor placed at the tertiary winding can reach very fine resolution of 1.3 kHz due to the impedance transformations and source degeneration. The bias and control voltages of nearly zero power are generated with a switched-capacitor based DC-DC converter and a ring-based non-overlapped clock generator.

Design of a 4.2-to-5.1 GHz Ultralow-Power Complementary Class-B/C Hybrid-Mode VCO in 65-nm CMOS Fully Supported by EDA Tools

Optimal voltage-controlled oscillator (VCO) design for ultralow-power (ULP) radios has to fulfill simultaneously multiple requirements such as frequency tuning range, phase noise, power consumption, and frequency pushing. The manual design struggles to approach the full potential that a given topology can achieve. In this work, we prove the role of electronic design automation (EDA) tools by fully supporting the complex design of a ULP complementary Class-B/C hybrid-mode VCO. In the 1st step of the EDA-assisted flow, we perform a worst-case corner of worst-case tuning sizing optimization over a 108-dimensional performance space, offering sizing solutions with power consumption down to $145~\mu \text{W}$ at the worst-case. In the 2nd step, we introduce an automatic layout generation tool to offer valuable insights into the post-layout design space and devise a ready-for-tape-out fine optimization strategy. The hybrid-mode VCO prototyped in 65-nm CMOS occupies a die area of 0.165 mm2 and dissipates $297~\mu \text{W}$ from a 0.8 V supply at 5.1 GHz. The phase noise at 1 MHz offset is −110.1 dBc/Hz, resulting in a competitive Figure-of-Merit (FoM) of 189.4 dBc/Hz well-suited for ULP applications.

A 5 GHz 0.5 V Hybrid Class-B/F−1 CMOS Oscillator With −147 dBc/Hz Phase Noise at 10 MHz Offset Using Body-Biased 22 nm FDSOI

This work presents a self-biased 5 GHz hybrid class-B/F−1 oscillator for low phase noise and robust startup. The design exploits the concurrent conduction of nMOS and pMOS, when placed on differential sides, to form a differential-mode (DM) high-quality-factor second-harmonic resonator for low phase noise. The same resonator is shared between the main core (class-F−1) and the startup core (class-B), to allow phase noise reduction. The hybrid CMOS oscillator is fabricated in 22 nm fully depleted silicon-on-insulator (FDSOI) using thin-oxide-only devices, operated from 0.5 V supply, and achieves a phase noise <−147 dBc/Hz at 10 MHz offset across 11% tuning range. The peak figure of merit (FoM) is 190 dBc/Hz, and the supply frequency pushing ranges from 20–44 MHz/V, whereas the power consumption is from 15 to 18 mW. To the authors’ knowledge, the hybrid class-B/F−1 oscillator delivers the lowest phase noise using a 0.5 V supply at 5 GHz.

Theoretical and experimental study on frequency pushing effect of magnetron**Project supported by the Sichuan Science and Technology Program, China (Grant No. 2019YFG0419) and the National Natural Science Foundation of China (Grant No. 61601312).

The applications of magnetrons are greatly limited because of the poor output spectrum of the free-running magnetron. Currently, one of the best ways to solve this problem is injection locking. However, the injection locking theory which is widely used nowadays is based on the simplified oscillator, which does not include the frequency pushing effect of the magnetron. In this paper, the theory of injection locking magnetrons with frequency pushing effect is systematically studied. Analytical analysis shows that the locking bandwidth turns larger with the consideration of the pushing parameter (α), and the increase of locking bandwidth is expanded with α increasing. Experimental results show that the locking bandwidth is expanded by 0.3 MHz, 1 MHz, and 1.6 MHz compared with the locking bandwidth from the conventional locking theory under an injection ratio (ρ) of 0.05, 0.075, and 0.1, respectively. This research provides a more accurate prediction of the properties of the injection-locked magnetron.

A Supply-Noise-Insensitive Digitally-Controlled Oscillator

A digitally controlled oscillator (DCO) is presented that utilizes the non-linearity of a resistor-triode combination in conjunction with a weak latch to mitigate the supply sensitivity of inverter-based delay cells and remain supply noise insensitive over a wide range of supply variation. A proof-of-concept prototype for the DCO in 65 nm-CMOS process occupies $90\times 210\,\,\mu \text{m}\,\,^{\mathrm{ 2}}$ area and consumes 2.25 mW operating over a range of 0.9–1.4 GHz output frequency. At 850 Mv-supply voltage, the frequency pushing of DCO is zero at the optimal point and remains less than 10% over a large excursion of 50 mVpp. When embedded into an all-digital phase locked loop, closed-loop measurements demonstrate that supply noise with 50 mVppmagnitude does not impact the loop dynamics.

A Noise Circulating Oscillator

This paper presents a noise circulating cross-coupled voltage-controlled oscillator (VCO) topology with a transformer-based tank. The introduced noise circulating active core greatly suppresses the effective noise power from the active devices while offering the same amount of negative resistance compared to conventional cross-coupled VCO topologies. The mechanism of noise circulation is investigated with theoretical analysis and further verified by simulation. Due to the broadband nature of the noise circulating technique, the resulting VCO phase noise in both 1/ $f^{2}$ and 1/ $f^{3}$ regions is greatly improved over a wide frequency tuning range. A prototype VCO at 2.35 GHz is implemented in a standard 130-nm bulk CMOS process with 0.36-mm2 core area. It draws 2.15 mA from a 1.2-V supply. The measured figure-of-merit (FoM) is 193.1/195.0/195.6 dBc/Hz at 100k/1M/10MHz offsets with a 1/ $f^{3}$ phase noise corner of only 50 kHz. The VCO design consistently achieves >192.8 dBc/Hz FoM at 100k/1M/10MHz offsets and $f^{3}$ phase noise corner over its entire 18.6% frequency tuning range (2.05 − 2.47 GHz). It also exhibits low supply frequency pushing of −25 and −13 MHz/V at the highest and lowest frequencies, respectively.

The High-Temperature Loading Influence on Orthorhombic Ni3Nb DOa δ - Phase Formation and its Effect on Fatigue Lifetime in Alloy 718

The orthorhombic DOa Ni3Nb delta phase is naturally presented in microstructure of cast or wrought Ni - Cr - Fe base alloy 718. It is a reason of chemical composition heterogeneity. For delta phase formation is a minimum Nb content about 8% needed and temperature above 650°C and higher. A typical place, where delta phase is situated are grain boundaries in alloy 718, where its role is discutable. Some references saying about lowering the mechanical properties when delta phase is segregated at grain boundary. To approve or disprove of this fact, the wrought alloy 718 with ASTM 12 grain size was subjected to high-temperature loading at push - pull fatigue at low cycle and low frequency (LCLF) and obtained results were compared to results from very high cycle and frequency (VHCF) push - pull loading datas obtained in previous experiments done at room temperature. To support results about influence of delta phase formation an observation on light microscopy and SEM was made too. To increase and make easier identification of delta phase, the techniques of polarised light (DIC - Differential Interferential Contrast) and dark-field (DF) observation were used too.

Anomalous Dielectric Behavior of a Pb/Sn Perovskite: Effect of Trapped Charges on Complex Photoconductivity

Organic–inorganic metal halide perovskites (MHPs) exhibit prominent electronic and optical properties benefiting the performance of solar cells and light-emitting diodes. However, the dielectric properties of these materials have remained poorly understood, despite probably influencing delayed charge recombination and device capacitance. Herein, we characterize the unprecedented dielectric behavior of MHPs comprising methylammonium cations, Pb/Sn as metals, and Br/I as halides using time-resolved microwave conductivity (TRMC) measurements. At specific compositions, the above MHPs exhibit negative real and positive imaginary photoconductivities, the polarities of which are opposite those observed for conventional photogenerated charge carriers. Comparing the observed TRMC kinetics with that of inorganic perovskites (SrTiO3 and BaTiO3) and characterizing its dependence on temperature, frequency, and near-infrared second push pulse, we conclude that the above behavior is due to the trapping of polaronic hole...

Simulation and Experiments of an $S$ -Band 20-kW Power-Adjustable Phase-Locked Magnetron

A 3-D particle-in-cell simulation model of a commercial industrial heating magnetron is developed as a guide for improving a fixed-output-power magnetron. After this improvement, the magnetron is transformed into a 20-kW power-adjustable phase-locked magnetron, which can then be injection-locked with tunable power output. For the first-time ever, the output power of the injection-locked magnetron is continuously tuned from 2 to 19 kW. This large-power magnetron is both phase and amplitude controlled, and is useful for the coherent power combining of multiple magnetrons. The magnetron frequency pushing effect, which affects the injection-locked frequency range of the phase-locked magnetron, is observed in both simulations and measurements. In the injection-locking experiments, the locking bandwidth varies from 11.7 to 2.4 MHz when the output power is tuned from 5 to 19.1 kW and the injection power is kept at 120 W. Moreover, the center frequency of the phase-locked magnetron increases with increasing output power.

A Bluetooth Low-Energy Transceiver With 3.7-mW All-Digital Transmitter, 2.75-mW High-IF Discrete-Time Receiver, and TX/RX Switchable On-Chip Matching Network

We present an ultra-low-power Bluetooth low-energy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F2 digital power amplifier (PA), featuring high efficiency. Low 1/ $f$ DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (~10 Gsamples/s) with intermediate frequency placed beyond 1/ $f$ noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE.

Standing wave plasmon modes interact in an antenna-coupled nanowire.

In a standing wave optical cavity, the coupling of cavity modes, for example, through a nonlinear medium, results in a rich variety of nonlinear dynamical phenomena, such as frequency pushing and pulling, mode-locking and pulsing, modal instabilities, even complex chaotic behavior. Metallic nanowires of finite length support a hierarchy of longitudinal surface plasmon modes with standing wave properties: the plasmonic analog of a Fabry-Pérot cavity. Here we show that positioning the nanowire within the gap of a plasmonic nanoantenna introduces a passive, hybridization-based coupling of the standing-wave nanowire plasmon modes with the antenna structure, mediating an interaction between the nanowire plasmon modes themselves. Frequency pushing and pulling, and the enhancement and suppression of specific plasmon modes, can be controlled and manipulated by nanoantenna position and shape.

On the tuning of high-resolution NMR probes.

Three optimum conditions for the tuning of NMR probes are compared: the conventional tuning optimum, which is based on radio-frequency pulse efficiency, the spin noise tuning optimum based on the line shape of the spin noise signal, and the newly introduced frequency shift tuning optimum, which minimizes the frequency pushing effect on strong signals. The latter results if the radiation damping feedback field is not in perfect quadrature to the precessing magnetization. According to the conventional RLC (resistor–inductor–capacitor) resonant circuit model, the optima should be identical, but significant deviations are found experimentally at low temperatures, in particular on cryogenically cooled probes. The existence of different optima with respect to frequency pushing and spin noise line shape has important consequences on the nonlinearity of spin dynamics at high polarization levels and the implementation of experiments on cold probes.

A Low Phase Noise Oscillator Principled on Transformer-Coupled Hard Limiting

Reduced phase noise conversion in a monolithic oscillator suitable for basestation applications is realized by hard limiting and subsequently restoring the resonating waveform. Overdriven transistors hard limit the drain voltage swing and it is shown analytically that this desensitizes the oscillation phase to circuit noise. A pair of tuned, 1:2 step-up transformers in the feedback path restore the fundamental frequency component with sufficient gain to overdrive the transistors forming the oscillator core, with greater selectivity than an equivalent LC tank. The 8 GHz, 65 nm CMOS oscillator prototype targeting the GSM-900 base-station specification consumes 32 mA from 1.5 V. Normalized to 915 MHz, the phase noise measured at 1 MHz offset is -147.7 dBc/Hz, validating predictions from theory and simulation. The measured frequency pushing is less than 16 MHz/V.