Showing papers on "Crystal oven published in 2004"

Resolution in quartz crystal oscillator circuits for high sensitivity microbalance sensors in damping media

Abstract: The use of quartz crystal oscillators as high sensitivity microbalance sensors is limited by the frequency noise present in the circuit. To characterise the behaviour of the sensors, it is not enough to determine their experimental sensitivity, but rather it is essential to study the frequency fluctuations in order to establish the sensor resolution. This is fundamental in the case of oscillators for damping media, because the level of noise rises due to the strong decline of the quality factor of the resonator. In this paper, a comparative study of noise and resolution is presented with respect to the frequency and the quality factor. The study has been made using four oscillators designed to be used in quartz crystal microbalance sensors in damping media. The four circuits have been designed at increasing frequencies in order to improve the sensitivity. Also, the current resolution limit of a microbalance oscillator is determined using an AT resonator, since this does not depend on the frequency. However, when working in liquid, the damping of the resonator makes the resolution diminish due to a worsening the quality factor. The relationship between the resolution limit and the frequency and characteristics of the liquid medium has been determined. The resolution worsens when the density and viscosity of the liquid is increased. However, in this case, the increase in frequency implies a small increase in the resolution. Therefore, when working below the maximum quality factor, for similar values, the resolution can be improved by elevating the work frequency.

Phase-locked carrier-envelope-offset frequency at 1560 nm.

Abstract: We report on the measurement of an Erbium-fiber oscillator’s carrier-envelope-offset frequency using an extruded SF6 photonic crystal fiber for the generation of a more than two octave-spanning supercontinuum from 400 nm to beyond 1750 nm. A modified type of f-2f-interferometer was employed, beating the frequency doubled input signal of the fiber oscillator with the supercontinuum to generate the carrier-envelope-offset beat. Controlling the fiber oscillator’s pump power with an electronic feedback loop, we phase-locked the carrier-envelope-offset frequency to an external reference source. The resulting residual phase excursions correspond to fractional frequency instabilities of the oscillator’s frequency comb of the order of 10-16 for averaging times longer than 10 s.

Device for detecting the temperature of an oscillator crystal

Abstract: In a device for detecting the temperature of an oscillator crystal 2 , arranged on a carrier, in particular in a mobile radio apparatus, the detected temperature should be as exact as possible a replica of the temperature to which the oscillator crystal 2 is subjected. For this purpose, a temperature sensor 7 is arranged on the carrier 1 in such a way that it is subjected to the same ambient temperature as the oscillator crystal 2 or the oscillator-crystal housing 2 ′. The temperature sensor 7 and the oscillator crystal 2 are located so as to be electrically parallel.

Crystal oscillator and detector

Abstract: PROBLEM TO BE SOLVED: To provide a compact crystal oscillator having low power consumption and satisfactory frequency temperature characteristics. SOLUTION: First and second oscillator 1A, 1B are used as an oscillator comprising a quartz oscillator and an oscillation circuit, and for example a heterodyne detector is provided for taking out a difference in oscillation frequencies from the oscillators 1A, 1B and outputting the frequency signal of the frequency difference. A resonance frequency at the first oscillator 1A differs from that at the second one 1B, and the frequency temperature characteristics are identical with those at the second oscillator 1B. COPYRIGHT: (C)2006,JPO&NCIPI

622 MHz high frequency fundamental composite crystal resonator with an air-gapped electrode

Abstract: We have developed a 622 MHz fundamental crystal resonator using composite wafers with an air-gapped electrode. To reduce the mass loading effect of the electrode, we introduced a three layer laminated quartz wafer and an air-gapped electrode. The electrical characteristics of the 622 MHz fundamental crystal resonator have satisfied the target specification by using a new process and structure.

Radio frequency temperature sensor and method of calibrating temperature therefor

Abstract: A radio frequency temperature sensor and a method of calibration temperature therefor are disclosed. An active radio frequency temperature sensor including a ring oscillator, a memory, a frequency counter, a radio frequency transmission interface and a micro-controller is used to calibrate and verify the efficacy of the radio frequency temperature sensor. Thereafter, a passive radio frequency temperature sensor including a regulator, a clock extractor, a ring oscillator, a memory, a frequency counter, a modulator and a state-machine is developed according to the verified results.

Amplitude control for crystal oscillator

Abstract: Circuits and methods for controlling the amplitude of oscillation of a crystal. In one example, a circuit may include a peak detector; a first voltage-to-current converter; a first current-to-voltage converter coupled with the first voltage-to-current converter; a second voltage-to-current converter; a second current-to-voltage converter coupled with the second voltage-to-current converter; and a differential amplifier; wherein a ratio between a size of first voltage-to-current converter and a size of the second voltage-to-current converter is used to control the gain of the circuit.

Miller oscillators for high sensitivity quartz crystal microbalance sensors in damping media

Abstract: The paper presents a new contribution to the design of quartz crystal oscillators for high sensitivity microbalance sensors used in liquid media. The oscillation condition for the Miller configuration was studied in order to optimize the values of the components to obtain oscillators for use in extreme conditions of damping. The equations relating the value of the active and passive components with the maximum supported damping and detected mass were obtained. A CAD tool was developed to help users in the design of microbalances adapted to the application requirements. To increase the mass sensitivity, four optimized microbalance circuits at augmenting frequencies were developed. The components of the circuits were optimized in order to maintain the oscillations in a wide dynamic range of resonator losses. A calibration of the sensors was made. To determine the real sensitivity of the mass sensors, the frequency noise was studied.

Direct mounting of quartz crystal on a CMOS PLL chip

Abstract: This paper reports progress on directly mounting a quartz crystal on a CMOS oscillator and PLL chip This approach minimizes the distance between the quartz crystal resonator and the oscillator circuitry and can allow reduced power with reduced stray coupling effects This approach also allows simplified packaging and can reduce the volume and weight of precision oscillators

Recent results on quartz crystal LD-cuts operating in oscillators

Abstract: These last few years, a new doubly rotated cut of quartz crystal resonator has been thought up at the LCEP (Laboratoire de Chronometrie Electronique et Piezoelectricite) This cut, named LD-cut for "low isochronism defect" cut, exhibits an amplitude-frequency effect one hundred times lower than the SC-cut one, that is to say a relative frequency change of about 1/spl middot/10/sup -11/ This paper deals with the behavior of such a crystal cut working in an oscillator It is based on results from a batch of 10 MHz LD-cuts recently manufactured in a BVA process Properties, advantages and drawbacks of the LD-cut are first reviewed They have been tested in terms of noise and then built in oscillators Experiments with various resonator drive levels have been performed Measurements of their power spectral density of phase fluctuations are given and discussed

Frequency offset correction techniques for crystals used in communication systems

Abstract: A method and system for pulling a crystal frequency are provided, thereby allowing wireless stations to use less accurate crystal oscillators and dramatically reduce cost. A first frequency offset can be determined using a temperature-based method. This temperature-base method can include detecting a temperature substantially that of the crystal oscillator and then using that temperature to determine the first frequency offset. A second frequency offset using a closed loop frequency estimate-based method can also be determined. This frequency estimate-based method can include synchronizing the crystal frequency to a presumed, accurate frequency of a controlling device to determine the second frequency offset. Both the first and second frequency offsets can be used to pull the crystal frequency. A synthesizer can also be pulled to fine tune a carrier frequency derived from the crystal frequency.

Methodology of design of electronic circuit oscillators for QCM sensors in liquid media

Abstract: This work deals with the development of a methodology for the design of electronic circuit oscillators for quartz crystal microbalance (QCM) applications in damping media. The developed methodology allows the design requirements of an oscillator topology to be obtained as a function of the resonator operating conditions (characteristics of the working media and of mass to sense). This methodology allows the oscillation condition to be studied and the critical values of the components, the possible oscillation areas and the optimal expressions that allow the losses maintaining the oscillation to be obtained.

The microcomputer compensated crystal oscillator - practical application of dual-harmonic mode quartz thermometry

Abstract: A precision frequency source based on dual harmonic mode quartz thermometry - Q-Tech's microcomputer compensated crystal oscillator (MCXO) is described. System architecture, thermometry, compensation method, environmental and long-term performance characteristics are presented. Problems arising from the need to employ frequency synthesis and discrete-time compensation are addressed. Test results indicate that an initial frequency-temperature stability of 1E-8 over a temperature range of -50/spl deg/C to +85/spl deg/C is readily achievable, but that long-term stability depends upon the unique resonator. Aging characteristics that have not been previously characterized for precision clocks and the dependence of long-term stability on the differential aging rate between resonator harmonic modes are presented.

Dual mode SC-cut crystal oscillator

Abstract: The simultaneous dual mode oscillation circuit of the 5 MHz 3/sup rd/ overtone SC-cut crystal is designed using mode-selective linear phase crystal filters, for each C and B mode. The perturbable dual mode oscillation has been successfully eliminated over the temperature range from -20/spl deg/ C to +90/spl deg/ C. Temperature regulation is also achieved using B mode oscillation frequency which provides the temperature information of the SC-cut quartz crystal itself. Over the temperature range of -20/spl deg/ C to +70/spl deg/ C, the temperature of the SC-cut crystal has been locked within /spl plusmn/0.002/spl deg/ C converted by the heat frequency between C and B modes. The total power consumption at supply voltage of 12V, is less than 2.4W at +25/spl deg/ C in still air.

The modern OCXO quartz oscillators requirements and parameters

Abstract: It seems that in last few years the quartz crystal precision oscillators OCXO did reach the limit of parameters improvement. Most of OCXO designers focused their attention on price reduction and practicability of oscillator construction. In Tele and Radio Research Institute new designs of OCXO oscillators fulfilling requirements of military standard MIL-STD-202G were made. In the paper there are described important requirements for military and civil OCXO oscillators and parameters of new designed oscillators. The results of new elaborated oscillators investigations show that the improvement of OCXO oscillators parameters is still possible.

Crystal oscillator, oscillation method, and heater

Abstract: PROBLEM TO BE SOLVED: To provide a crystal oscillator that can oscillate stably, at the same time, as well as with oscillation signal by means of two oscillation modes of a quartz oscillator. SOLUTION: The output of the quartz oscillator Xtal is inputted to B and C mode sides, i.e., two crystal oscillator F11, F12 and F21, F22, respectively. Then, transistors Tr11, Tr12 and Tr21, Tr22 perform phase coupling of these outputs. By this, a signal having phase and gain stable with respect to frequency variation is obtained and therefore, stable oscillation is carried out. In addition, a beat signal is used to perform temperature compensation control, and the crystal resonator Xtal is heated from its terminal. COPYRIGHT: (C)2005,JPO&NCIPI

Measurement of short-term stability of ultra stable oscillators

Abstract: We present in this paper the progress report of the building of two cryogenic sapphire oscillators (CSO) at LPMO. A description of our original resonator configuration is discussed. The measurement of a short-term frequency instability better than 2middot10 -14 for short integration times is presented. We also demonstrated an exceptional long term frequency stability of better than 5middot10 -14 over one day. We finally report the usefullness of CSO in the characterization of state of the art ultra stable quartz cristal oscillators in a simple way of measurement.

Mitigation of Multi-Oscillation in a Low Voltage Colpitts Crystal Oscillator

Abstract: A variation of the Colpitts crystal oscillator based on a modification of the Butler structure and capable of driving the quartz crystal when the power supply has a low voltage value is presented. The addition of a grounded inductor with an appropriate value to the Colpitts circuit, without the need of a series resonance branch, is a non-bridged single solution that improves the excitation gradient of the crystal and, moreover, the spectral purity of the generated wave is enhanced. Also, it is reduced the circuit sensitivity with respect to crystal parameters. The resulting circuit requires only a reduced number of components, thus being suitable to be implemented as analogue integrated circuits.

Temperature compensation type crystal oscillator

Abstract: PROBLEM TO BE SOLVED: To provide a temperature compensation type crystal oscillator which is easily handled and excellent in productivity. SOLUTION: The temperature compensation type crystal oscillator is configured in such a way that a rectangular container body housing a crystal vibration element in the inside is fixed on a supporting base, and that an IC element for outputting an oscillation signal corresponding to the oscillation frequency of the crystal vibration element while correcting the oscillation signal on the basis of temperature compensation data, and a plurality of packaging legs disposed along the external periphery of the supporting base, are attached on the bottom surface of the supporting base. On the external peripheral region of the bottom surface of the supporting base, a writing control terminal consisting of a metallic post for writing temperature compensation data into the IC element is attached between adjacent packaging legs so as to be spaced from the packaging legs, the distance in side face between the writing control terminal and the packaging legs is set so as to be gradually wide from the outward to the inward, and a part of a resin material for covering the IC element is allowed to flow into the gap between the packaging legs and the writing control terminal. COPYRIGHT: (C)2005,JPO&NCIPI

Ultra low drift cryogenic sapphire microwave oscillator

Abstract: The paper presents the achievement of an exceptional long term frequency stability with a cryogenic-sapphire resonator oscillator (CSRO). The cryogenic resonator is based on an open cavity structure initially designed to suppress spurious modes and improve the resonance line shape and hence coupling.

Double temperature compensated crystal oscillator

Abstract: This paper introduces a double temperature compensated TCXO which combines two different compensation techniques The crystal oscillator is compensated with an analogue approach firstly, then compensated secondly with a digital approach based on an improved frequency temperature performance According to the frequency temperature characteristics of the VCTCXO, a microprocessor generates the secondary compensation voltage after processing With the voltage as the control signal to the VCTCXO, the frequency-temperature stability of the crystal oscillator can be compensated into /spl plusmn/2/spl sim/3/spl times/10/sup -7/ in a -55/spl deg/C to +90/spl deg/C temperature range Utilizing this method, the demand on the secondary compensation is decreased noticeably and the structure can be very simple The temperature compensated crystal oscillator, based on the double compensation, is of low cost and shows less susceptibility to power supply instability and has better reliability Compared with ordinary DTCXO and MCXO, based on AT cut crystals, it is easier to produce

Limit parameters of GPS disciplined quartz frequency sources

Abstract: Fivefold decrease of RMS jitter of 1 pps pulse from GPS receiver after SA switch-off and relatively short period required to filter it out has enabled the construction of GPS synchronized frequency sources of parameters almost order of magnitude better than with SA. New design challenge has been to achieve 10-11 frequency accuracy over time period of 1000 seconds. Basic block diagram of GPS disciplined frequency source is presented in fig 1. The only non purely digital blocks of the source are quartz oscillator and digital to analog converter D/A and their specs decide about the parameters of the output frequency signal. Design requirements for internal quartz oscillator as well as digital to analog converter based on required minimal frequency control loop time of about 10000 seconds have been derived and presented. To summarize, quartz oscillator has to exhibit aging not worse than 3 • 10-11/24h and temperature coefficient 1•10-12/°C while digital to analog converter has to be an 18-bit device with 1 LSB differential nonlinearity and extremely low temperature coefficient. Alternately as devices with very low temperature drift are very expensive, the converter can take its reference voltage from the oscillator, where the reference source is temperature stabilized. This of course places higher demands on the oscillator voltage reference source.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Method and system featuring frequencies of crystal resonator

Abstract: PROBLEM TO BE SOLVED: To provide a technique for profiling or featuring of frequency outputs from a crystal, based oscillator reducing the deviations of frequency, due to the influence of environment. SOLUTION: This is a technology for deciding the frequency profiles of crystal resonators in real time. Of the crystal resonator experiencing a series of temperature cycles with various temperature variabilities, the crystal frequencies, the crystal temperature parameter and the temperature variability are monitored, when the crystal resonator experiences temperature cycles. Then, the monitored frequencies are classified, related to the monitored temperature parameters and the temperature variability. The system for deciding the frequencies of crystal resonator includes a processor for implementing the frequency profiling technology. COPYRIGHT: (C)2005,JPO&NCIPI

Noise conversion in crystal oscillators

Abstract: This paper discusses the noise performance of a crystal oscillator. It is assumed that the crystal resonator motional losses, inductance, and capacity as well as its static capacity are flicker noisy. The Johnson thermal additive noise of the motional losses is also taken into account. To convert the intrinsic noise sources to the amplitude and phase fluctuations, the crystal resonator and the feedback amplifier are performed by noisy impedances. The crystal oscillator is reduced to the closed loop of the resonator impedance and the feedback amplifier impedance. The transformation coefficients are derived to convert the resonator and amplifier amplitude and phase power spectral density functions to those of the oscillator amplitude and phase. Noise performance of a crystal oscillator with different excitation angles of a resonator is studied in detail.