Crystal VCO center frequency stabilizer

1977 ◽  
Author(s):  
E. Gray Jensen
Keyword(s):  
Center Frequency

Power Efficient Implementation of Low Noise CMOS LC VCO using 32nm Technology for RF Applications

2018 ◽  
Vol 6 (8) ◽  
pp. 53
Author(s):  
Shitesh Tiwari ◽  
Sumant Katiyal ◽  
Parag Parandkar
Keyword(s):  
Power Consumption ◽  
Phase Noise ◽  
Tuning Range ◽  
Low Voltage ◽  
Performance Comparison ◽  
Low Noise ◽  
Center Frequency ◽  
Voltage Controlled Oscillator ◽  
Low Phase Noise ◽  
Lc Vco

Voltage Controlled Oscillator (VCO) is an integral component of most of the receivers such as GSM, GPS etc. As name indicates, oscillation is controlled by varying the voltage at the capacitor of LC tank. By varying the voltage, VCO can generate variable frequency of oscillation. Different VCO Parameters are contrasted on the basis of phase noise, tuning range, power consumption and FOM. Out of these phase noise is dependent on quality factor, power consumption, oscillation frequency and current. So, design of LC VCO at low power, low phase noise can be obtained with low bias current at low voltage.  Nanosize transistors are also contributes towards low phase noise. This paper demonstrates the design of low phase noise LC VCO with 4.89 GHz tuning range from 7.33-11.22 GHz with center frequency at 7 GHz. The design uses 32nm technology with tuning voltage of 0-1.2 V. A very effective Phase noise of -114 dBc / Hz is obtained with FOM of -181 dBc/Hz. The proposed work has been compared with five peer LC VCO designs working at higher feature sizes and outcome of this performance comparison dictates that the proposed work working at better 32 nm technology outperformed amongst others in terms of achieving low Tuning voltage and moderate FoM, overshadowed by a little expense of power dissipation. 

Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-Frequency Underwater Imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Yuanyu Yu ◽  
Jiujiang Wang ◽  
Xin Liu ◽  
Sio Hang Pun ◽  
Weibao Qiu ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
Center Frequency ◽  
Design Parameters ◽  
Underwater Imaging ◽  
Release Process ◽  
Steel Wires ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
Frequency Ultrasound

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.

scholarly journals Aperiodic Flux Variability in A 0535+262

1996 ◽  
Vol 165 ◽  
pp. 313-319
Author(s):  
Mark H. Finger ◽  
Robert B. Wilson ◽  
B. Alan Harmon ◽  
William S. Paciesas
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Beat Frequency ◽  
Power Spectra ◽  
Center Frequency ◽  
X Ray ◽  
Binary Pulsar ◽  
Transient Source ◽  
Flux Variability ◽  
Burst And Transient Source

A “giant” outburst of A 0535+262, a transient X-ray binary pulsar, was observed in 1994 February and March with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory. During the outburst power spectra of the hard X-ray flux contained a QPO-like component with a FWHM of approximately 50% of its center frequency. Over the course of the outburst the center frequency rose smoothly from 35 mHz to 70 mHz and then fell to below 40 mHz. We compare this QPO frequency with the neutron star spin-up rate, and discuss the observed correlation in terms of the beat frequency and Keplerian frequency QPO models in conjunction with the Ghosh-Lamb accretion torque model.

scholarly journals An 18.8–33.9 GHz, 2.26 mW Current-Reuse Injection-Locked Frequency Divider for Radar Sensor Applications

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2551
Author(s):  
Kwang-Il Oh ◽  
Goo-Han Ko ◽  
Jeong-Geun Kim ◽  
Donghyun Baek
Keyword(s):  
Supply Voltage ◽  
Cmos Technology ◽  
Frequency Divider ◽  
Oxide Semiconductor ◽  
Center Frequency ◽  
Radar Sensor ◽  
Frequency Locking ◽  
Current Reuse ◽  
Sensor Applications ◽  
Locking Range

An 18.8–33.9 GHz, 2.26 mW current-reuse (CR) injection-locked frequency divider (ILFD) for radar sensor applications is presented in this paper. A fourth-order resonator is designed using a transformer with a distributed inductor for wideband operating of the ILFD. The CR core is employed to reduce the power consumption compared to conventional cross-coupled pair ILFDs. The targeted input center frequency is 24 GHz for radar application. The self-oscillated frequency of the proposed CR-ILFD is 14.08 GHz. The input frequency locking range is from 18.8 to 33.8 GHz (57%) at an injection power of 0 dBm without a capacitor bank or varactors. The proposed CR-ILFD consumes 2.26 mW of power from a 1 V supply voltage. The entire die size is 0.75 mm × 0.45 mm. This CR-ILFD is implemented in a 65 nm complementary metal-oxide semiconductor (CMOS) technology.

scholarly journals Analysis method of the cavitation vibration signals in poppet valve based on EEMD

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Beibei Li ◽  
Qiao Zhao ◽  
Huaiyi Li ◽  
Xiumei Liu ◽  
Jichao Ma ◽  
...  
Keyword(s):  
Ensemble Empirical Mode Decomposition ◽  
Center Frequency ◽  
Analysis Method ◽  
Vibration Signals ◽  
Poppet Valve ◽  
Mode Decomposition ◽  
Marginal Spectrum ◽  
Cavitation Intensity ◽  
Eemd Method ◽  
Peak Value

To study the vibration characteristics of the poppet valve induced by cavitation, the signal analysis method based on the ensemble empirical mode decomposition (EEMD) method was studied experimentally. The component induced by cavitation was separated from the vibration signals through the EEMD method. The results show that the IMF2 component has the largest amplitude and energy of all components. The root mean square (RMS) value, peak value of marginal spectrum, and center frequency of marginal spectrum of the IMF2 component were studied in detail. The RMS value and the peak value of the marginal spectrum decrease with a decrease of cavitation intensity. The center frequency of marginal spectrum is between 12 kHz and 20 kHz, and the center frequency first increases and then decreases with a decrease of cavitation intensity. The change rate of the center frequency also decreases with an increase of inlet pressure.

scholarly journals Encapsulation of Capacitive Micromachined Ultrasonic Transducers (CMUTs) for the Acoustic Communication between Medical Implants

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 421
Author(s):  
Jorge Oevermann ◽  
Peter Weber ◽  
Steffen H. Tretbar
Keyword(s):  
Data Security ◽  
Ultrasonic Transducers ◽  
Surrounding Tissue ◽  
Center Frequency ◽  
Medical Implants ◽  
Research Groups ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Polyether Ether Ketone ◽  
High Bandwidth ◽  
Ether Ketone

The aim of this work was to extend conventional medical implants by the possibility of communication between them. For reasons of data security and transmitting distances, this communication should be realized using ultrasound, which is generated and detected by capacitive micromachined ultrasonic transducers (CMUTs). These offer the advantage of an inherent high bandwidth and a high integration capability. To protect the surrounding tissue, it has to be encapsulated. In contrast to previous results of other research groups dealing with the encapsulation of CMUTs, the goal here is to integrate the CMUT into the housing of a medical implant. In this work, CMUTs were designed and fabricated for a center frequency of 2 MHz in water and experimentally tested on their characteristics for operation behind layers of Polyether ether ketone (PEEK) and titanium, two typical materials for the housings of medical implants. It could be shown that with silicone as a coupling layer it is possible to operate a CMUT behind the housing of an implant. Although it changes the characteristics of the CMUT, the setup is found to be well suited for communication between two transducers over a distance of at least 8 cm.

scholarly journals Multiple Narrowband Interferences Characterization, Detection and Mitigation Using Simplified Welch Algorithm and Notch Filtering

2021 ◽  
Vol 11 (3) ◽  
pp. 1331
Author(s):  
Mohammad Hossein Same ◽  
Gabriel Gleeton ◽  
Gabriel Gandubert ◽  
Preslav Ivanov ◽  
Rene Jr Landry
Keyword(s):  
Power Spectrum ◽  
Embedded System ◽  
Radio Frequency ◽  
Satellite Communication ◽  
Signal To Noise Ratio ◽  
Center Frequency ◽  
Infinite Impulse Response ◽  
Frequency Variation ◽  
Welch Method ◽  
The Embedded System

By increasing the demand for radio frequency (RF) and access of hackers and spoofers to low price hardware and software defined radios (SDR), radio frequency interference (RFI) became a more frequent and serious problem. In order to increase the security of satellite communication (Satcom) and guarantee the quality of service (QoS) of end users, it is crucial to detect the RFI in the desired bandwidth and protect the receiver with a proper mitigation mechanism. Digital narrowband signals are so sensitive into the interference and because of their special power spectrum shape, it is hard to detect and eliminate the RFI from their bandwidth. Thus, a proper detector requires a high precision and smooth estimation of input signal power spectral density (PSD). By utilizing the presented power spectrum by the simplified Welch method, this article proposes a solid and effective algorithm that can find all necessary interference parameters in the frequency domain while targeting practical implantation for the embedded system with minimum complexity. The proposed detector can detect several multi narrowband interferences and estimate their center frequency, bandwidth, power, start, and end of each interference individually. To remove multiple interferences, a chain of several infinite impulse response (IIR) notch filters with multiplexers is proposed. To minimize damage to the original signal, the bandwidth of each notch is adjusted in a way that maximizes the received signal to noise ratio (SNR) by the receiver. Multiple carrier wave interferences (MCWI) is utilized as a jamming attack to the Digital Video Broadcasting-Satellite-Second Generation (DVB-S2) receiver and performance of a new detector and mitigation system is investigated and validated in both simulation and practical tests. Based on the obtained results, the proposed detector can detect a weak power interference down to −25 dB and track a hopping frequency interference with center frequency variation speed up to 3 kHz. Bit error ratio (BER) performance shows 3 dB improvement by utilizing new adaptive mitigation scenario compared to non-adaptive one. Finally, the protected DVB-S2 can receive the data with SNR close to the normal situation while it is under the attack of the MCWI jammer.

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