scholarly journals Noise Properties of Two Mutually Coupled Spin-Transfer Nanooscillators in the Phase Locking Regime

2020 ◽  
Vol 23 (2) ◽  
pp. 19-25
Author(s):  
A. A. Mitrofanov ◽  
A. R. Safin ◽  
E. M. Torina ◽  
N. N. Udalov
Keyword(s):  
Phase Noise ◽  
Phase Synchronization ◽  
Frequency Tuning ◽  
Spectral Power ◽  
Phase Locking ◽  
Magnetic Nanostructures ◽  
Mutual Synchronization ◽  
Attenuation Coefficients ◽  
Synchronization Mode ◽  
Wide Range

Introduction. Today, many research endeavors are devoted to the miniaturization of microwave sources. One of the promising approaches is the use of magnetic nanostructures (spintronics elements), providing a wide range of frequency tuning and low power consumption. The main disadvantage of spintronics generators (spintransfer nanoscillators ‒ STNO) is a low output power of generated oscillations (tens of nanowatts and less). A possible solution is to sum up the power of many STNOs in a mutual synchronization mode.Aim. The investigation of noise properties of two connected STNOs with identical and non-identical parameters in a phase synchronization mode.Materials and methods. A model was developed of two STNOs interconnected by spin waves taking into account thermal noises. Spectral power densities of the amplitude and phase noise were obtained by the method of effective linearization.Results. Dependencies were obtained in a general form for attenuation coefficients of the amplitude and phase fluctuations of noise sources for each STNO. Three cases of synchronization were considered: completely identical STNOs, two identical STNOs but with different oscillation frequencies, and two non-identical STNOs, differing in an allowance of self-excitation by frequencies and amplitudes of the oscillations. It was possible to obtain a gain in the amplitude and phase noise for two identical STNOs. In this case, an increase in the allowance of self-excitation led to a decrease in the level of phase and amplitude noise.Conclusion. This analysis of the attenuation coefficients for non-identical STNOs demonstrates the possibility of improving the noise properties of each of the generators. In this case, the best noise value is obtained for an STNO with greater stability in a stand-alone mode.

scholarly journals A Design of Wide-Range and Low Phase Noise Linear Transconductance VCO with 193.76 dBc/Hz FoMT for mm-Wave 5G Transceivers

Electronics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 935 ◽  
Author(s):  
Arash Hejazi ◽  
YoungGun Pu ◽  
Kang-Yoon Lee
Keyword(s):  
Phase Noise ◽  
Carrier Frequency ◽  
Tuning Range ◽  
Frequency Tuning ◽  
Cmos Process ◽  
Switched Capacitor ◽  
Voltage Controlled Oscillator ◽  
Wide Range ◽  
Layout Area ◽  
Low Phase Noise

This paper presents a wide-range and low phase noise mm-Wave Voltage Controlled Oscillator (VCO) based on the transconductance linearization technique. The proposed technique eliminates the deep triode region of the active part of the VCO, and lowers the noise introduced by the gm-cell. The switch sizes inside the switched capacitor bank of the VCO are optimized to minimize the resistance of the switches while keeping the wide tuning range. A new layout technique shortens the routing of the VCO outputs, and lowers the parasitic inductance and resistance of the VCO routing. The presented method prevents the reduction of the quality factor of the tank due to the long routing. The proposed VCO achieves a discrete frequency tuning range, of 14 GHz to 18 GHz, through a linear coarse and middle switched capacitor array, and offers superior phase noise performance compared to recent state-of-the-art VCO architectures. The design is implemented in a 45 nm CMOS process and occupies a layout area (including output buffers) of 0.14 mm2. The power consumption of the VCO core is 24 mW from the power supply of 0.8 V. The post-layout simulation result shows the VCO achieves the phase noise performances of −87.2 dBc/Hz and −113 dBc/Hz, at 100 kHz and 1 MHz offset frequencies from the carrier frequency of 14 GHz, respectively. In an 18 GHz carrier frequency, the results are −87.4 dBc/Hz and −110 dBc/Hz, accordingly.

scholarly journals Low Phase Noise and Wide-Range Class-C VCO Using Auto-Adaptive Bias Technique

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1290
Author(s):  
Jeong-Yun Lee ◽  
Gwang Sub Kim ◽  
Goo-Han Ko ◽  
Kwang-Il Oh ◽  
Jae Gyeong Park ◽  
...  
Keyword(s):  
Phase Noise ◽  
Tuning Range ◽  
Frequency Tuning ◽  
Wide Frequency Range ◽  
Cmos Process ◽  
Voltage Controlled Oscillator ◽  
Frequency Range ◽  
Wide Range ◽  
Class C ◽  
Low Phase Noise

This paper proposes a new structure of 24-GHz class-C voltage-controlled oscillator (VCO) using an auto-adaptive bias technique. The VCO in this paper uses a digitally controlled circuit to eliminate the possibility of start-up failure that a class-C structure can have and has low phase noise and a wide frequency range. To expand the frequency tuning range, a 3-bit cap-bank is used and a triple-coupled transformer is used as the core inductor. The proposed class-C VCO implements a 65-nm RF CMOS process. It has a phase noise performance of −105 dBc/Hz or less at 1-MHz offset frequency and the output frequency range is from 22.8 GHz to 27.3 GHz, which consumes 8.3–10.6 mW of power. The figure-of-merit with tuning range (FoMT) of this design reached 191.1 dBc/Hz.

WAVEGUIDE-COAXIAL RESONATOR WITH WIDE-RANGE FREQUENCY TUNING AND INCREASED Q-FACTOR

2016 ◽  
Vol 75 (10) ◽  
pp. 887-894 ◽  
Author(s):  
R. I. Bilous ◽  
A. P. Motornenko ◽  
I. G. Skuratovskiy ◽  
O. I. Khazov
Keyword(s):  
Frequency Tuning ◽  
Q Factor ◽  
Coaxial Resonator ◽  
Wide Range

scholarly journals Controlling and Phase‐Locking a THz Quantum Cascade Laser Frequency Comb by Small Optical Frequency Tuning

2021 ◽  
pp. 2000417
Author(s):  
Luigi Consolino ◽  
Annamaria Campa ◽  
Michele De Regis ◽  
Francesco Cappelli ◽  
Giacomo Scalari ◽  
...  
Keyword(s):  
Quantum Cascade Laser ◽  
Frequency Tuning ◽  
Frequency Comb ◽  
Phase Locking ◽  
Laser Frequency ◽  
Optical Frequency ◽  
Quantum Cascade

Spatial-frequency and orientation tuning in psychophysical end-stopping

1998 ◽  
Vol 15 (4) ◽  
pp. 585-595 ◽  
Author(s):  
CONG YU ◽  
DENNIS M. LEVI
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Spatial Filter ◽  
Orientation Tuning ◽  
Maximal Strength ◽  
Facilitation Effect ◽  
Spatial Filters ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Wide Range

A psychophysical analog to cortical receptive-field end-stopping has been demonstrated previously in spatial filters tuned to a wide range of spatial frequencies (Yu & Levi, 1997a). The current study investigated tuning characteristics in psychophysical spatial filter end-stopping. When a D6 (the sixth derivative of a Gaussian) target is masked by a center mask (placed in the putative spatial filter center), two end-zone masks (placed in the filter end-zones) reduce thresholds. This “end-stopping” effect (the reduction of masking induced by end-zone masks) was measured at various spatial frequencies and orientations of end-zone masks. End-stopping reached its maximal strength when the spatial frequency and/or orientation of the end-zone masks matched the spatial frequency and/or orientation of the target and center mask, showing spatial-frequency tuning and orientation tuning. The bandwidths of spatial-frequency and orientation tuning functions decreased with increasing target spatial frequency. At larger orientation differences, however, end-zone masks induced a secondary facilitation effect, which was maximal when the spatial frequency of end-zone masks equated the target spatial frequency. This facilitation effect might be related to certain types of contour and texture perception, such as perceptual pop-out.

Monaural inhibition in cat auditory cortex

1995 ◽  
Vol 73 (5) ◽  
pp. 1876-1891 ◽  
Author(s):  
M. B. Calford ◽  
M. N. Semple
Keyword(s):  
Auditory Cortex ◽  
Lateral Inhibition ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Inhibitory Response ◽  
Forward Masking ◽  
Excitatory Response ◽  
Rate Level ◽  
Wide Range ◽  
Response Area

1. Several studies of auditory cortex have examined the competitive inhibition that can occur when appropriate sounds are presented to each ear. However, most cortical neurons also show both excitation and inhibition in response to presentation of stimuli at one ear alone. The extent of such inhibition has not been described. Forward masking, in which a variable masking stimulus was followed by a fixed probe stimulus (within the excitatory response area), was used to examine the extent of monaural inhibition for neurons in primary auditory cortex of anesthetized cats (barbiturate or barbiturate-ketamine). Both the masking and probe stimuli were 50-ms tone pips presented to the contralateral ear. Most cortical neurons showed significant forward masking at delays beyond which masking effects in the auditory nerve are relatively small compared with those seen in cortical neurons. Analysis was primarily concerned with such components. Standard rate-level functions were also obtained and were examined for nonmonotonicity, an indication of level-dependent monaural inhibition. 2. Consistent with previous reports, a wide range of frequency tuning properties (excitatory response area shapes) was found in cortical neurons. This was matched by a wide range of forward-masking-derived inhibitory response areas. At the most basic level of analysis, these were classified according to the presence of lateral inhibition, i.e., where a probe tone at a neuron's characteristic frequency was masked by tones outside the limits of the excitatory response area. Lateral inhibition was a property of 38% of the sampled neurons. Such neurons represented 77% of those with nonmonotonic rate-level functions, indicating a strong correlation between the two indexes of monaural inhibition; however, the shapes of forward masking inhibitory response areas did not usually correspond with those required to account for the "tuning" of a neuron. In addition, it was found that level-dependent inhibition was not added to by forward masking inhibition. 3. Analysis of the discharges to individual stimulus pair presentations, under conditions of partial masking, revealed that discharges to the probe occurred independently of discharges to the preceding masker. This indicates that even when the masker is within a neuron's excitatory response area, forward masking is not a postdischarge habituation phenomenon. However, for most neurons the degree of masking summed over multiple stimulus presentations appears determined by the same stimulus parameters that determine the probability of response to the masker.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Field-aligned chorus wave spectral power in Earth's outer radiation belt

2015 ◽  
Vol 33 (5) ◽  
pp. 583-597 ◽  
Author(s):  
H. Breuillard ◽  
O. Agapitov ◽  
A. Artemyev ◽  
E. A. Kronberg ◽  
S. E. Haaland ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Radiation Belt ◽  
Spectral Power ◽  
Peak Frequency ◽  
Wave Power ◽  
Outer Radiation Belt ◽  
Substantial Impact ◽  
Wide Range ◽  
Frequency Variations ◽  
Chorus Wave

Abstract. Chorus-type whistler waves are one of the most intense electromagnetic waves generated naturally in the magnetosphere. These waves have a substantial impact on the radiation belt dynamics as they are thought to contribute to electron acceleration and losses into the ionosphere through resonant wave–particle interaction. Our study is devoted to the determination of chorus wave power distribution on frequency in a wide range of magnetic latitudes, from 0 to 40°. We use 10 years of magnetic and electric field wave power measured by STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus wave spectral power, as well as PEACE and RAPID measurements to model the properties of energetic electrons (~ 0.1–100 keV) in the outer radiation belt. The dependence of this distribution upon latitude obtained from Cluster STAFF-SA is then consistently reproduced along a certain L-shell range (4 ≤ L ≤ 6.5), employing WHAMP-based ray tracing simulations in hot plasma within a realistic inner magnetospheric model. We show here that, as latitude increases, the chorus peak frequency is globally shifted towards lower frequencies. Making use of our simulations, the peak frequency variations can be explained mostly in terms of wave damping and amplification, but also cross-L propagation. These results are in good agreement with previous studies of chorus wave spectral extent using data from different spacecraft (Cluster, POLAR and THEMIS). The chorus peak frequency variations are then employed to calculate the pitch angle and energy diffusion rates, resulting in more effective pitch angle electron scattering (electron lifetime is halved) but less effective acceleration. These peak frequency parameters can thus be used to improve the accuracy of diffusion coefficient calculations.

scholarly journals Wide range frequency tuning in vacuum electronic devices

2003 ◽  
Author(s):  
V.G. Baryshevsky ◽  
K.G. Batrakov ◽  
N.A. Belous ◽  
A.A. Gurinovich ◽  
A.S. Lobko ◽  
...  
Keyword(s):  
Frequency Tuning ◽  
Electronic Devices ◽  
Wide Range ◽  
Vacuum Electronic Devices

scholarly journals Activity-dependent myelination: A glial mechanism of oscillatory self-organization in large-scale brain networks

2020 ◽  
Vol 117 (24) ◽  
pp. 13227-13237 ◽  
Author(s):  
Rabiya Noori ◽  
Daniel Park ◽  
John D. Griffiths ◽  
Sonya Bells ◽  
Paul W. Frankland ◽  
...  
Keyword(s):  
White Matter ◽  
Large Scale ◽  
Phase Synchronization ◽  
Brain Networks ◽  
Self Organization ◽  
Conduction Delay ◽  
Neural Communication ◽  
Wide Range ◽  
The Impact ◽  
Activity Dependent

Communication and oscillatory synchrony between distributed neural populations are believed to play a key role in multiple cognitive and neural functions. These interactions are mediated by long-range myelinated axonal fiber bundles, collectively termed as white matter. While traditionally considered to be static after development, white matter properties have been shown to change in an activity-dependent way through learning and behavior—a phenomenon known as white matter plasticity. In the central nervous system, this plasticity stems from oligodendroglia, which form myelin sheaths to regulate the conduction of nerve impulses across the brain, hence critically impacting neural communication. We here shift the focus from neural to glial contribution to brain synchronization and examine the impact of adaptive, activity-dependent changes in conduction velocity on the large-scale phase synchronization of neural oscillators. Using a network model based on primate large-scale white matter neuroanatomy, our computational and mathematical results show that such plasticity endows white matter with self-organizing properties, where conduction delay statistics are autonomously adjusted to ensure efficient neural communication. Our analysis shows that this mechanism stabilizes oscillatory neural activity across a wide range of connectivity gain and frequency bands, making phase-locked states more resilient to damage as reflected by diffuse decreases in connectivity. Critically, our work suggests that adaptive myelination may be a mechanism that enables brain networks with a means of temporal self-organization, resilience, and homeostasis.

Intrinsic Frequency Tuning in ELL Pyramidal Cells Varies Across Electrosensory Maps

2008 ◽  
Vol 99 (5) ◽  
pp. 2641-2655 ◽  
Author(s):  
W. Hamish Mehaffey ◽  
Leonard Maler ◽  
Ray W. Turner
Keyword(s):  
Sensory Input ◽  
Frequency Tuning ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Pyramidal Cells ◽  
Weakly Electric Fish ◽  
Systematic Change ◽  
Specific Stimulus ◽  
Wide Range ◽  
Sensory Maps

The tuning of neuronal responsiveness to specific stimulus frequencies is an important computation across many sensory modalities. The weakly electric fish Apteronotus leptorhynchus detects amplitude modulations of a self-generated quasi-sinusoidal electric organ discharge to sense its environment. These fish have to parse a complicated electrosensory environment with a wide range of possible frequency content. One solution has been to create multiple representations of the sensory input across distinct maps in the electrosensory lateral line lobe (ELL) that participate in distinct behavioral functions. E- and I-type pyramidal cells in the ELL that process sensory input further exhibit a preferred range of stimulus frequencies in relation to the different behaviors and sensory maps. We tested the hypothesis that variations in the intrinsic spiking mechanism of E- and I-type pyramidal cells contribute to map-specific frequency tuning. We find that E-cells exhibit a systematic change in their intrinsic spike characteristics and frequency tuning across sensory maps, whereas I-cells are constant in both spike characteristics and frequency tuning. As frequency tuning becomes more high-pass in E-cells, the refractory variables of spike half-width and afterhyperpolarization magnitude increase, spike threshold increases, adaptation becomes faster, and the gain of the spiking response decreases. These findings indicate that frequency tuning across sensory maps in the ELL is supported by differences in the intrinsic spike characteristics of pyramidal cells, revealing a link between cellular biophysical properties and signal processing in sensory maps with defined behavioral roles.

Sign in / Sign up

Export Citation Format

Share Document