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Showing papers on "Frequency drift published in 2007"


Journal ArticleDOI
TL;DR: The paper describes the design and implementation of an electronically temperature compensated reference oscillator based on capacitive silicon micromechanical resonators that exhibits a frequency drift of 39 ppm over 100degC as compared to an uncompensated frequency drift over the same range.
Abstract: The paper describes the design and implementation of an electronically temperature compensated reference oscillator based on capacitive silicon micromechanical resonators. The design of a 5.5-MHz silicon bulk acoustic resonator has been optimized to offer high quality factor (> 100 000) while maintaining tunability in excess of 3000 ppm for fine-tuning and temperature compensation. Oscillations are sustained with a CMOS amplifier. When interfaced with the temperature compensating bias circuit, the oscillator exhibits a frequency drift of 39 ppm over 100degC as compared to an uncompensated frequency drift of 2830 ppm over the same range. The sustaining amplifier and compensation circuitry were fabricated in a 2P3M 0.6-mum CMOS process.

126 citations


Patent
14 Sep 2007
TL;DR: In this paper, an oscillator operable to generate a foldover signal indicating when the frequency of the oscillator signal is decreasing due to the first voltage exceeding a threshold is described.
Abstract: Control circuitry is disclosed including an oscillator operable to generate an oscillator signal. A frequency of the oscillator signal increases as an amplitude of a first voltage increases up to a threshold, and the frequency of the oscillator signal decreases as an amplitude of the first voltage exceeds the threshold. The oscillator is operable to generate a foldover signal indicating when the frequency of the oscillator signal is decreasing due to the first voltage exceeding the threshold.

115 citations


Journal ArticleDOI
TL;DR: For such an extremely low-power receiver, current-reusing and frequency multiplying schemes are proposed for both the RF front-end and frequency source, which achieves a conversion gain and a noise figure suitable for wireless sensor network applications.
Abstract: In this paper, we present a receiver front-end and a frequency source suitable for wireless sensor network applications, in which power consumption is severely restricted under several milliwatts. For such an extremely low-power receiver, current-reusing and frequency multiplying schemes are proposed for both the RF front-end and frequency source. The proposed front-end achieves a conversion gain of 30.5 dB and a noise figure of 10.2 dB at the 10-MHz intermediate frequency (IF), taking only 500-muA bias current from a 1.0-V supply voltage. The measured phase noise of the fabricated frequency source is -115.83 dBc/Hz at 1 MHz offset from a 2.2-GHz center frequency, taking 840 muA from a 0.7-V supply. The front-end performance is compared with the previously reported low-power front-ends operating in similar frequency ranges

85 citations


Journal ArticleDOI
TL;DR: In this article, a rotary traveling-wave oscillator is used to generate the output signals at the 30 GHz frequency band for 15/30 GHz dual-band applications, and the proposed circuit is fabricated in a standard 0.18mum CMOS process with a chip area of 1.1times1.0 mm2.
Abstract: A multiphase oscillator suitable for 15/30-GHz dual-band applications is presented. In the circuit implementation, the 15-GHz half-quadrature voltage-controlled oscillator (VCO) is realized by a rotary traveling-wave oscillator, while frequency doublers are adopted to generate the quadrature output signals at the 30-GHz frequency band. The proposed circuit is fabricated in a standard 0.18-mum CMOS process with a chip area of 1.1times1.0 mm2. Operated at a 2-V supply voltage, the VCO core consumes a dc power of 52 mW. With a frequency tuning range of 250 MHz, the 15-GHz half-quadrature VCO exhibits an output power of -8 dBm and a phase noise of -112 dBc/Hz at 1-MHz offset frequency. The measured power level and phase noise of the 30-GHz quadrature outputs are -16 dBm and -104 dBc/Hz, respectively

74 citations


Patent
07 Mar 2007
TL;DR: In this article, a parametric-insensitive reference oscillator is used as a reference to measure frequency performance of a second oscillator wherein the second oscillators performance is parametric sensitive.
Abstract: An integrated circuit is used to monitor and process parametric variations, such as temperature and voltage variations. An integrated circuit may include a temperature-sensitive oscillator circuit and a temperature-insensitive oscillator circuit, and frequency difference between the two sources may be monitored. In some embodiments, a parametric-insensitive reference oscillator is used as a reference to measure frequency performance of a second oscillator wherein the second oscillator performance is parametric-sensitive. The measured frequency performance is then compared to a tamper threshold and the result of the comparison is indicative of tampering.

64 citations


Journal ArticleDOI
TL;DR: In this paper, the authors performed an automated analysis of 230 high-resolution dynamic spectra of S-bursts, providing 5 × 10 6 frequency drift measurements and confirmed over a large number of measurements that the frequency drift d f / d t (f ) is in average negative and decreases (in absolute value) at high frequencies, as predicted by the adiabatic theory.

61 citations


Journal ArticleDOI
TL;DR: In this article, the authors show that close to the transition between the island and the banana state, 4U~1636--53 shows mHz quasi-periodic oscillations whose frequency systematically decreases with time until the oscillations disappear and a Type I X-ray burst occurs.
Abstract: Millihertz quasi-periodic oscillations reported in three neutron-star low mass X-ray binaries have been suggested to be a mode of marginally stable nuclear burning on the neutron star surface. In this Letter, we show that close to the transition between the island and the banana state, 4U~1636--53 shows mHz QPOs whose frequency systematically decreases with time until the oscillations disappear and a Type I X-ray burst occurs. There is a strong correlation between the QPO frequency $ u$ and the occurrence of X-ray bursts: when $ u\gtrsim9$ mHz no bursts occur, while $ u\lesssim9$ mHz does allow the occurrence of bursts. The mHz QPO frequency constitutes the first identified observable that can be used to predict the occurrence of X-ray bursts. If a systematic frequency drift occurs, then a burst happens within a few kilo-seconds after $ u$ drops below 9 mHz. This observational result confirms that the mHz QPO phenomenon is intimately related with the processes that lead to a thermonuclear burst.

54 citations


Journal ArticleDOI
TL;DR: The proposed iterative-loop approaching algorithm can respond to the supply frequency variation, the fundamental amplitude/phase variation, as well as the harmonics frequency amplitude/ phase variation instantly and accurately.
Abstract: With the increasing use of power electronic devices in the past decade, the produced harmonic pollution to the power supply is aggravating power supply quality. The monitoring of the health state of a power network is therefore becoming an essential issue. Although conventional techniques like discrete Fourier transform or fast Fourier transform are still widely applied in industry, some limitations arise particularly under supply frequency drift and transient circumstances. The proposed iterative-loop approaching algorithm can respond to the supply frequency variation, the fundamental amplitude/phase variation, as well as the harmonics frequency amplitude/phase variation instantly and accurately. Furthermore, an abrupt change of fundamental frequency and amplitude can also be traced properly and promptly. Numerical examples supporting the performance of the proposed algorithm are presented

51 citations


Proceedings ArticleDOI
27 May 2007
TL;DR: The design of an on-chip RC-based oscillator, implemented in a standard 0.35 mum CMOS process, without any external component, is presented.
Abstract: The design of an on-chip RC-based oscillator, implemented in a standard 0.35 mum CMOS process, without any external component, is presented. The proposed oscillator provides a clock signal at a frequency of about 80 KHz with a temperature coefficient smaller than 842 ppm/degC over a temperature range from 0 to 80 7degC and a standard deviation due to process variations smaller than 4%, without any external trimming. The proposed oscillator operates with a supply voltage of 1 V and has a power consumption of about 1 muW at room temperature. The chip area is 0.24 mm2.

49 citations


Patent
23 May 2007
TL;DR: In this paper, the authors present a system, method and apparatus for frequency calibration of a free-running, reference harmonic oscillator, which comprises the harmonic oscillators, a frequency divider, a comparator, and a reactance modulator.
Abstract: Exemplary embodiments of the invention provide a system, method and apparatus for frequency calibration of a free-running, reference harmonic oscillator. An exemplary system comprises the harmonic oscillator, a frequency divider, a comparator, and a reactance modulator. The reference harmonic oscillator includes a plurality of switchable reactance modules controlled by corresponding coefficients, and provides an oscillation signal having an oscillation frequency, which is divided or multiplied by the frequency divider to provide an output signal having an output frequency. The comparator compares the output frequency to an externally supplied reference frequency using first and second predetermined levels of discrimination, and provides first or second comparison signals when the output frequency is higher or lower than the reference frequency. The reactance modulator determines a plurality of coefficients to control switching of the plurality of switchable reactance modules to increase or decrease a reactance of the oscillator in response to the first and second comparison signals.

43 citations


Journal ArticleDOI
TL;DR: In this article, an analytical theory for Pound-Drever-Hall laser frequency stabilization using spectral hole-burning is developed, where the interaction between the atomic medium and the phase modulated light is described using a linearized model of the Maxwell-Bloch equations.
Abstract: There have recently been several studies of the performance of laser frequency stabilization using spectral holes in solids, instead of an external cavity, as a frequency reference. Here an analytical theory for Pound-Drever-Hall laser frequency stabilization using spectral hole-burning is developed. The interaction between the atomic medium and the phase modulated light is described using a linearized model of the Maxwell-Bloch equations. The interplay between the carrier and modulation sidebands reveals significant differences from the case of locking to a cavity. These include a different optimum modulation index, an optimum sample absorption, and the possibility to lock the laser in an inherent linear frequency drift mode. Spectral holes in solids can be permanent or transient. For the materials normally used, the dynamics and time scales of transient holes often depend on population relaxation processes between ground state hyperfine levels. These relaxation rates can be very different for different solid state materials. We demonstrate, using radio-frequency pumping, that the hyperfine population dynamics may be controlled and tailored to give optimum frequency stabilization performance. In this way also materials with initially non-optimum performance can be used for stabilization. The theoretical predictions regarding the inherent linear frequency drift is compared to experimental data from a dye laser stabilized to a spectral hole in a Pr3+:Y2SiO5 crystal.

Journal ArticleDOI
TL;DR: A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated, which showed broad bandwidths with respect to both LO and IF frequencies.
Abstract: A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated. The frequency up-converter converted an optical intermediate frequency (IF) signal (fIF = 2.5 GHz) to an optical radio frequency (RF) signal (fRF = 35 and 40 GHz) through mixing with an optical local oscillator (LO) signal (fLO = 37.5 GHz). The up-converter showed positive conversion efficiency of 5.77 dB for the optical IF power of -22 dBm and the optical LO power of -13 dBm. This scheme showed broad bandwidths with respect to both LO and IF frequencies. The up-converter showed a phase noise of -84.5 dBc/Hz for the LO frequency of 37.5 GHz (fLO) and the offset frequency of 10 kHz after the frequency up-conversion.

Journal ArticleDOI
TL;DR: In this article, a sub-millimeter-wave HBT oscillator is reported, which uses a single-emitter 0.3 m15 m InP HBT device with a maximum frequency of oscillation greater than 500 GHz.
Abstract: In this paper, a sub-millimeter-wave HBT oscillator is reported. The oscillator uses a single-emitter 0.3 m15 m InP HBT device with maximum frequency of oscillation greater than 500 GHz. The passive components of the oscillator are realized in a two metal process with benzocyclobutene used as the primary transmission line dielectric. The oscillator is implemented in a common base topology due to its inherent instability. The design includes an on-chip resonator, output matching circuitry, and injection locking port. A free-running frequency of 311.6 GHz has been measured by down-converting the signal. Additionally, injection locking has been successfully demonstrated with up to 17.8 dB of injection-locking gain. This is the first fundamental HBT oscillator operating above 300 GHz.

Journal ArticleDOI
TL;DR: In this paper, a multicycle synchronous digital phase measurement is proposed to further improve the phase measurement in phase-shift laser range finding, where heterodyne processing is employed to convert the phase measurements of a high frequency signal into that of a low frequency signal, and by keeping phase measurement independent of the signal frequency to be measured and the gate signal synchronous with the measurement signal during multicycle phase measurement, errors caused by the frequency drift of a local oscillator during conventional auto-digital phase measurement are totally eliminated.
Abstract: Multicycle synchronous digital phase measurement is proposed in this paper to further improve the phase measurement in phase-shift laser range finding. In the method, heterodyne processing is employed to convert the phase measurement of a high frequency signal into that of a low frequency signal, and by keeping phase measurement independent of the signal frequency to be measured and the gate signal synchronous with the measurement signal during multicycle phase measurement, errors caused by the frequency drift of a local oscillator during conventional auto-digital phase measurement are totally eliminated, and the time required to complete range measurement is shortened. Experimental results show that an uncertainty better than ?1.5 mm can be achieved at a data rate up to 20 Hz (t = 0.05 s) for a laser range finder using the method proposed with fe = 10.000 MHz.

Journal ArticleDOI
TL;DR: It is verified that the measurement accuracy of the prototype depends on the nominal frequency and the level of the sinusoidal voltages, but it does not depend on the initial phase difference and offset frequency.
Abstract: We propose a novel measurement system that evaluates the frequency stability of high-precision oscillators such as atomic oscillators. This measurement system consists of a pair of high-speed analog-to-digital converters (ADCs) and digital-signal-processing (DSP) circuits on a field programmable gate array. The pair of high-speed ADCs simultaneously digitizes the two sinusoidal-voltage outputs from the oscillator under test and a reference oscillator. The DSP circuits calculate the phase difference between the two sinusoidal voltages. The frequency stability evaluated as the Allan deviation sigmay(tau) is calculated from the phase difference. The main advantage of this system is that the hardware configuration is much more compact than the conventional systems using a dual mixer and a local oscillator. Nonetheless, the system noise floor of the prototype at the nominal frequency of 5 MHz is sigmay(1000 s) = 6.8 times 10-17, which is sufficient to evaluate a commercial hydrogen maser oscillator and is better by a factor of 5 than our previously reported system. We have verified that the measurement accuracy of the prototype depends on the nominal frequency and the level of the sinusoidal voltages, but it does not depend on the initial phase difference and offset frequency.

Patent
Yossi Tsfaty1
24 Aug 2007
TL;DR: In this article, a non-integer multiplication ratio between the local oscillator and RF frequencies is used to generate I and Q square waves at a designated frequency while avoiding the well known issue of harmonic pulling.
Abstract: A novel and useful apparatus for and method of local oscillator (LO) generation with non-integer multiplication ratio between the local oscillator and RF frequencies. The LO generation schemes presented are operative to generate I and Q square waves at a designated frequency while avoiding the well known issue of harmonic pulling. An input baseband signal is interpolated and upconverted in the digital domain to an IF. The LO operates at a frequency which is a n/m division of the target RF frequency f RF . The IF frequency is configured to ½ of the LO frequency. The upconverted IF signal is then converted to the analog domain via digital power amplifiers followed by voltage combiners. The output of the combiners is band pass filtered to extract the desired replica.

Patent
23 May 2007
TL;DR: In this article, a reference harmonic oscillator integrated circuit having three or more terminals is described, with systems and methods for calibrating the oscillator to a selected first frequency using a limited number of terminals.
Abstract: Exemplary embodiments of the invention provide a reference harmonic oscillator integrated circuit having three or more terminals, with systems and methods for calibrating the harmonic oscillator to a selected first frequency using a limited number of terminals An exemplary apparatus comprises: a reference harmonic oscillator, a first terminal to receive a supply voltage, a second terminal to receive a ground potential, a third terminal to provide an output signal having an output frequency, and may also include a fourth terminal One of the first, second, third or fourth terminals is further adapted for input of a calibration of the first frequency The exemplary apparatus may enter calibration and testing modes in response to various commands such as a calibration mode signal, and may also be configured through one of the terminals for output frequency selection, spread-spectrum output, and output voltage levels

Journal ArticleDOI
François Léonard1
TL;DR: In this paper, a frequency spectrogram is calculated from the phase difference between each time slice of the Short Time Fourier Transform (STFT) and the reference frequency for each component, which shows the drift on the instantaneous frequency of each spectral component.

Patent
18 Jul 2007
TL;DR: In this article, a dynamic low-interference avoidance receiver shifts the local oscillator frequency to avoid image interference and shifts the center frequency of the band pass filter to track the frequency shift.
Abstract: A dynamic low IF image interference avoidance receiver shifts the local oscillator frequency to avoid image interference and shifts the center frequency of the band pass filter to track the frequency shift of the local oscillator or uses two local oscillators, a first to shift frequency and separate the desired frequency and image interference frequency and the second to track the first and maintain the output IF at a fixed frequency

Patent
12 Jul 2007
TL;DR: In this article, a startup circuit for a tunable oscillator based oscillator is described, where the frequency of the tunable frequency is adjusted such that the frequency is substantially equal to the resonant frequency of a resonator-based oscillator.
Abstract: A startup circuit 200 and method 700 is provided for quickly starting up a resonator based oscillator. Tunable oscillator 201 provides an impetus signal to oscillator 205 through capacitor 202 . The impetus signal has a frequency that is an estimate of the resonant frequency of resonator 205 . The circuit measures the frequency of oscillator 204 and the frequency of tunable oscillator 201 . The circuit then adjusts the frequency of tunable oscillator 201 such that the frequency of the tunable oscillator is substantially equal to the resonant frequency of the resonator 205 and stores a data state necessary for the tunable oscillator 201 to generate a signal with this target frequency in the future. During an ensuing startup cycle the stored data state causes the impetus signal delivered by tunable oscillator 202 to be substantially equal to the target frequency of oscillator 204 which improves startup performance.

Patent
08 Oct 2007
TL;DR: In this paper, a silicon resonator of the tuning-fork type is described, where the linear frequency drift depending on the temperature is compensated by a silicon layer provided between two layers of silicon oxide having a thickness relative to that of the silicon layer.
Abstract: The invention relates to a silicon resonator (10) of the tuning-fork type in which the linear frequency drift depending on the temperature is compensated. The resonator comprises a silicon base (14), a plurality of parallel arms (11, 12, 13) capable of vibrating and actuation means (18, 21, 22), wherein said arms include a silicon layer provided between two layers of silicon oxide having a thickness, relative to that of the silicon layer, such that it ensures the first-order compensation of the resonator thermal drift.

Patent
05 Dec 2007
TL;DR: A self-calibrating temperature compensated oscillator includes a monolithic structure having a first resonator, a second resonator and a heating element to heat the first and second resonators as discussed by the authors.
Abstract: A self-calibrating temperature compensated oscillator includes a monolithic structure having a first resonator, a second resonator, and a heating element to heat the first and second resonators. The temperature coefficient of the second resonator is substantially greater than the temperature coefficient of the first resonator. A first oscillator circuit operates with the first resonator and outputs a first oscillator output signal having a first oscillating frequency. A second oscillator circuit operates with the second resonator and outputs a second oscillator output signal having a second oscillating frequency. A temperature determining circuit determines the temperature of the first resonator using the second oscillating frequency. A temperature compensator provides a control signal to the first oscillator in response to the determined temperature to adjust the first oscillating frequency and maintain it at a desired operating frequency.

Patent
07 Nov 2007
TL;DR: In this paper, a charge pump circuit includes a voltage controlled oscillator, which operates at a lower frequency during warm-up mode, and at a higher frequency during a loading mode, to reduce power supply current requirements.
Abstract: A charge pump circuit includes a voltage controlled oscillator The voltage controlled oscillator operates at a lower frequency during a warm-up mode, and operates at a higher frequency during a loading mode The lower frequency operation during the warm-up mode reduces power supply current requirements

Patent
Nobuhiro Shiramizu1, Toru Masuda1
29 Jun 2007
TL;DR: In this article, a voltage-to-current conversion circuit that converts input control voltage to control current of a ring oscillator to the ring oscillators where delay circuits a delay time of which increases and decreases according to the amplitude of input control current are cascade-connected by a plurality of stages in a ring and increasing/decreasing current dependent upon any of temperature, supply voltage and the threshold voltage of a transistor inside the voltage to current conversion circuit.
Abstract: In a variable frequency oscillator in a semiconductor device, as the variation of an oscillation frequency caused by the variation of temperature and supply voltage and process variation is large, it is difficult to reduce the conversion ratio of control voltage dependent upon phase noise and the oscillation frequency and therefore, phase noise is large. The variation of the oscillation frequency is suppressed and phase noise is reduced by connecting a voltage-to-current conversion circuit that converts input control voltage to control current of a ring oscillator to the ring oscillator where delay circuits a delay time of which increases and decreases according to the amplitude of input control current are cascade-connected by a plurality of stages in a ring and increasing/decreasing current dependent upon any of temperature, supply voltage and the threshold voltage of a transistor inside the voltage-to-current conversion circuit.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed a series of tens of drifting microwave bursts during the 30 March 2001 flare and found that the contribution of the increasing density effect into the observed frequency drift rates is about 6 GHz s−1.
Abstract: Magnetic reconnection is commonly accepted to play a key role in flare energy release, but only poor information about the main characteristics of this process is available so far An intrinsic feature of reconnection is plasma density enhancement in current sheets A unique method to detect this effect is provided by analysis of drifting bursts, whose emission frequency is close to the local Langmuir frequency or its harmonics With this purpose, we analyze a series of several tens of drifting microwave bursts during the 30 March 2001 flare The burst drift rates range from −10 to 20 GHz s−1 Using one-dimensional scans recorded with the SSRT interferometer at two different frequencies near 57 GHz, we have measured relative positions of burst sources and their velocities along a flare loop revealed from soft X-ray and extreme-ultraviolet images It is argued that the contribution of the increasing density effect into the observed frequency drift rates is about 6 GHz s−1, which is shown to be consistent with theoretical models of magnetic reconnection with reasonable boundary conditions

Journal ArticleDOI
TL;DR: In this article, a cross-correlation analysis is used to quantify the dispersive time delay between each frequency of a chorus element as it arrives at Cluster spacecraft pairs and then compared with a ray-tracing technique in order to identify source locations that are consistent with the observed delays.
Abstract: [1] We report Cluster Wideband Data (WBD) receiver observations of correlated chorus elements with different frequency/time characteristics as seen on multiple spatially separated Cluster spacecraft. Because chorus packets disperse as they propagate, careful comparison of the signals from multiple spacecraft can provide new information about the origin of these waves. A cross-correlation analysis is used to quantify the dispersive time delay between each frequency of a chorus element as it arrives at Cluster spacecraft pairs. This data cross-correlation is then compared with a ray-tracing technique in order to identify source locations that are consistent with the observed delays. We also consider a time-variable source that emits frequencies that increase as a function of time. This frequency drift rate is adjusted to force the frequency/time variation of the simulated chorus element on a single spacecraft to match that observed. This process yields possible source locations for each spacecraft, whose location and extent are a function of the amount of source frequency emission drift. By requiring the individual spacecraft source regions to intersect with the multispacecraft source regions, a common static source region at L ∼ 3.9 (McIlwain parameter) and MLAT ∼ −5.9° (magnetic latitude) is identified for a single event (event 1) and upper and lower bounds are placed on the amount of source emission frequency drift within the source. No common source region is found for a second event (event 2).

Proceedings ArticleDOI
26 Dec 2007
TL;DR: In this article, a passively temperature compensated CMOS oscillator utilizing Film Bulk Acoustic Resonator (FBAR) was presented, which exhibited f-Q product of 2~3times1012 sec-1 is comprised of molybdenum (Mo), aluminum nitride (AlN), and a compensation material having positive temperature coefficient of Young's modulus.
Abstract: This paper presents a passively temperature compensated CMOS oscillator utilizing Film Bulk Acoustic Resonator (FBAR). The resonator exhibiting f-Q product of 2~3times1012 sec-1 is comprised of molybdenum (Mo), aluminum nitride (AlN), and a compensation material that has positive temperature coefficient of Young's modulus. The 600 MHz oscillator consumes 6.6 mW from a 3.3 V supply and achieves an excellent phase noise performance of -102 dBc/Hz, -132 dBc/Hz, and -151 dBc/Hz at 1 kHz, 10 kHz, and 100 kHz carrier offset, respectively. The oscillator's temperature-dependent frequency drift is less than 80 parts per million (ppm) over a temperature range of -35 to +85degC.

Journal ArticleDOI
TL;DR: In this article, the analysis of the radio observations of December 1, 2004 from 07:00 to 07:40 UTC in the 1.100 to 1.340 GHz band by solar broadband radio dynamic spectrometer (SBRS) in Huairou Station is presented.

Proceedings ArticleDOI
01 Nov 2007
TL;DR: In this article, a digitally controlled oscillator (DCO) with an enhanced frequency resolution and an extended linear frequency tuning range was reported. But the frequency resolution was not improved. And the frequency band has 2048 linear tuning levels with a frequency step of 5 kHz.
Abstract: This paper reports a LC-based digitally controlled oscillator (DCO) with an enhanced frequency resolution and an extended linear frequency tuning range It has a center frequency of 33 GHz and a frequency tuning range of 600 MHz covered by 64 different frequency bands Each frequency band has 2048 linear tuning levels with a frequency step of 5 kHz This DCO was implemented in 90 nm CMOS and the measured frequency tuning characteristics arc provided in this paper The DCO exhibits a phase noise of -11 NdBc/Hz at 1 MHz frequency offset The DCO core consumes 2 mA current from 12 V supply

Journal ArticleDOI
TL;DR: In this article, a long lasting narrow-band (4-7 mHz) fluctuation event at geosynchronous orbit is presented through measurements from GOES-8 and GoES-10 and the response of energetic electrons with drift frequencies close to the narrowband pulsation frequency is monitored through a spectral analysis of flux data from the LANL-SOPA energetic electron instrument.
Abstract: . A long lasting narrow-band (4–7 mHz) Pc5 fluctuation event at geosynchronous orbit is presented through measurements from GOES-8 and GOES-10 and the response of energetic electrons with drift frequencies close to the narrow-band pulsation frequency is monitored through a spectral analysis of flux data from the LANL-SOPA energetic electron instrument. This analysis shows electron flux modulations at the magnetospheric pulsation's frequency as well as at various other frequencies in the Pc5 range, related to the particles' drift-frequencies and their harmonics. A drift resonance effect can be seen, with electron flux modulation becoming more evident in the energy channels of electrons with drift frequencies closer to the wave frequency; however no net increase or decrease in energetic electron flux is observed, indicating that the net energy transfer and transport of electrons is not significant. This Pc5 event has a long duration, being observed for more than a couple of days at geosynchronous orbit over several traversals of the two GOES satellites, and is localized in azimuthal extent. Spectral analysis shows that most of the power is in the transverse components. The frequency of the narrow-band event, as observed at geosynchronous orbit shifts during the time of the event from 7±0.5 mHz to about 4±0.5 mHz. On the ground, CARISMA magnetometers record no distinct narrow-band fluctuation in the magnetic field, and neither does Geotail, which is traversing the outer magnetosphere a few RE further out from geosynchronous orbit, at the same UT and LT that GOES-8 and -10 observe the pulsations, suggesting that that there is no connection to external fluctuations originating in the solar wind. An internal generation mechanism is suggested, such as could be provided by energetic ring current particles, even though conclusive evidence could not be provided for this particular event. Through a statistical study, it is found that this event belongs to a class of similar events, occurring predominantly in the post-noon region in the inner magnetosphere.