Showing papers on "Crystal oven published in 2009"

Method for manufacturing a quartz crystal unit

Abstract: In a method for manufacturing a quartz crystal unit, a quartz crystal tuning fork resonator is formed by etching a quartz crystal wafer to form a quartz crystal tuning fork base, quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, and a groove having stepped portions in at least one of opposite main surfaces of each of the quartz crystal tuning fork tines. A first electrode is disposed on at least one of the stepped portions of each of the grooves and a second electrode is disposed on each of side surfaces of each of the quartz crystal tuning fork tines. A frequency of oscillation of the quartz crystal tuning fork resonator is adjusted at least twice and in different steps. The quartz crystal tuning fork resonator is then mounted in a case and an open end of the case is covered with a lid.

Oven controlled multistage crystal oscillator

Abstract: An object of the invention is to provide an oven controlled crystal oscillator that prevents a reduction in characteristics due to temperature rise in the crystal vibrator and circuit elements other than the oscillating stage, and that increases energy efficiency of a heater element, to thereby facilitate temperature control. The oven controlled crystal oscillator of the invention is an oven controlled multistage crystal oscillator provided with: a crystal vibrator; circuit elements of an oscillating stage, a buffering stage, and a temperature control circuit; and first, second, and third circuit substrates, wherein the configuration is such that: on the first circuit substrate or the second circuit substrate, there are arranged the heater element and the circuit element of the oscillating stage thermally bonded to the heater element; on the third circuit substrate, there are arranged the circuit element of the buffering stage, and at least the circuit elements of the temperature control circuit excluding the heater element and the temperature sensor element; and the third circuit substrate is distanced in the vertical direction and thermally isolated, with a clearance, from the first and second circuit substrates.

An oscillator circuit for dual-harmonic tracking of frequency and resistance in quartz resonator sensors

Abstract: An oscillator circuit is proposed that simultaneously excites and tracks two harmonic resonances in a quartz crystal resonator sensor. The oscillator outputs two pairs of signals, related to the sensor series resonant frequency and motional resistance for the fundamental and the third harmonic, respectively. The circuit also provides compensation of the sensor parallel capacitance for increased accuracy. By probing the resonator with the superposition of two harmonic modes simultaneously, enhanced sensing capabilities can be advantageously achieved because a larger set of parameters can be measured with a single sensor and its response is tracked in real time. Experimental tests were first run with the developed oscillator connected to 5 MHz AT-cut crystals exposed to different liquid solutions, obtaining results in good agreement with the theory. Evidence of different dynamic responses at the fundamental and the third harmonic was obtained, possibly related to differences in acoustic penetration depth into the liquid. The oscillator was then tested with the sensor loaded by microdroplets of liquid solutions deposited by a piezoelectric microdispenser. The oscillator could detect and track the resulting time response of the sensor, outperforming measurement methods based on impedance analysis in terms of speed and resolution, and evidencing a complex combination of effects in the sensor transient response.

Temperature-corrected frequency control with crystal oscillators

Abstract: A wireless communication terminal includes a crystal oscillator, a transceiver and circuitry. The crystal oscillator belongs to a specified type of crystal oscillators in which a dependence of an output frequency as a function of temperature has one or more parameters that vary among the crystal oscillators belonging to the specified type. The transceiver is arranged to perform signal processing operations to a communication signal using the output frequency of the crystal oscillator. The circuitry is arranged to determine a characteristic of the output frequency of the crystal oscillator at one or more operating temperatures, to compute the one or more parameters for the crystal oscillator based on the determined characteristic and the operating temperatures, and to correct a frequency error in the output frequency of the crystal oscillator using the dependence and the computed parameters.

A quartz crystal sensor oscillator appropriate for highly viscous liquid measurements

Abstract: This study describes a sensor oscillator appropriate for quartz crystal microbalance (QCM) based measurements in highly viscous liquids. The oscillator is stabilized by a recently developed impedance transformation QCM filter network which greatly reduces electrical load by the sustaining amplifier. In addition, it provides zero phase and a well-behaved symmetric resonance at the QCM series resonant frequency fs over three orders of magnitude variation range of the motional resistance Rm. The sustaining amplifier has constant pure resistive input and output impedances to eliminate phase shifts due to QCM impedance changes with liquid load. Also, it allows precise gain and phase control for accurate adjustment of the oscillator frequency at fs and extraction of Rm information at the measured liquid load. The oscillator was tested with different water-based glycerol solutions in the 40–100 wt% range. The worst-case frequency error was 4.7% in this viscosity range.

Electrical characterization of a tuning fork crystal oscillator using dual-phase lock-in technique

Abstract: We performed an electrical characterization of a tuning fork crystal oscillator using a dual-phase lock-in amplifier. Direct measurements of the complex admittance allowed us to extract all four values of the equivalent circuit model components of the tuning fork crystal oscillator.

Effects of radiation on performance of space-borne quartz crystal oscillators

Abstract: An essential component of any space vehicle is the onboard master oscillator. The proper operation of the entire payload is dependent on the performance of the master oscillator (or onboard clock). One of the major concerns for quartz clocks in space is the effect of space radiation. Quartz is inherently sensitive to naturally occurring radiation in space. The exact nature of the radiation experienced in space is a function of the orbital dynamics of each particular application, and the impact of that radiation on quartz oscillator performance depends on each particular mission's requirements. Extensive tests on Earth have revealed some very interesting results that can be used to predict performance in space. This has made possible the development of a radiation compensated quartz crystal oscillator, with improved frequency aging performance. The frequency aging rate is extremely important for predicting the expected performance of these oscillators after 10 or 15 years in space. In this paper we will present data on the effects of oscillator aging-rate performance when subject to some commonly encountered space radiation environments.

Acceleration “G” compensated quartz crystal oscillators

Abstract: High dynamic environments common to most platforms in motion such as helicopters, track-vehicles, ships, missiles and even spacecraft degrade the performance of quartz crystal oscillators. To generate the precise frequencies and time signals crucial to system performance quartz crystal oscillators and rubidium vapor atomic oscillators are commonly utilized. However quartz crystal oscillators whether stand alone or parts of traditional rubidium oscillators, exhibit degraded performance when subject to accelerating forces, i.e. sine and/or random vibrations. Although the spacecraft environment has traditionally been considered “vibration-free,” it is increasingly clear that low level accelerations and vibrations due to reaction wheels, thrusters, etc. degrade quartz oscillator output enough to impact, in many cases, system level performance. In addition, mechanical vibrations in ground stations/gateways degrade quartz oscillator performance and greatly affect beam-forming networks for communications satellites. In this paper we shall discuss a “g” (acceleration) compensated technology that has greatly increased the performance of quartz crystal oscillators in challenging environments. We will present data on technology break-through in two main areas (a) new methods of quartz resonator design and manufacturing that result in minimum cross-coupling between the three resonator axes and (b) new sensing devices that can be mounted and aligned in each resonator axis. In addition, we will present actual test data for oscillators performing in high “g” environments as well as lower “g” environments such as in spacecraft and ground stations/gateways.

Mode-coupling and phase-injection mechanism enables EMI-insensitive crystal oscillator circuits

Abstract: We report a novel crystal oscillator circuit using mode-coupling and phase-injection techniques for improved electromagnetic interference (EMI), start-up, and drive-level, dynamics for the realization of high frequency reference frequency standards. Experimental results and CAD simulated data provides insight into observed characteristics and validated with the 155.6 MHz crystal oscillator (XO).

Crystal oscillator, and measurement method using same

Abstract: A crystal oscillator, and a measurement method using same are provided with which the density of a solution can be measured alone, or both the density and the viscosity of a solution can be measured at the same time using a single detector provided for the crystal oscillator. A material to be measured is contacted to the crystal oscillator, and the crystal oscillator that includes electrodes formed on both surfaces of a piezoelectric plate, and an uneven-surface formed either on one of the electrodes disposed on the side in contact with the material to be measured, or on a detector formed on the electrode is oscillated. An amount of change in frequency (f2) that corresponds to the high-frequency side of two frequencies that represent a half value of a conductance maximum value of the crystal oscillator is measured to measure a density of the material.

Temperature compensated oscillation circuits

Abstract: A temperature compensated oscillation circuit capable of providing a stable frequency output over temperature is provided, in which an oscillator with a crystal resonator is arranged to generate an oscillation signal with an output frequency, and a temperature sensor provides a temperature compensation voltage of which a function is linear with respect to an ambient temperature of the oscillator. A first accumulation mode MOS varactor is coupled to the oscillator, and the first accumulation mode MOS varactor adjusts a capacitance thereof in response to the temperature compensation voltage, such that the coupled oscillator has a frequency compensation over temperature for the oscillation signal, wherein the frequency compensation substantially varies as an inverse function of a deviation of the crystal resonator over temperature when the ambient temperature is within a predetermined temperature range.

The effect of power-drive level on the calibration of the bridge instrument for the measurement of the quartz stability

Abstract: In this paper, it is shown that the amplitude-frequency effect, a well known phenomenon in quartz crystal resonator, questions the short-term stability results of quartz crystal resonators computed from phase noise measurement in passive interferometer systems This equipment allows one to measure the inherent phase stability of quartz crystal resonators in a passive circuit without the noise usually associated with an active oscillator The short-term stability of the resonator given by the Allan standard deviation is usually computed with the Leeson frequency A new method to characterize the short-term stability of crystal resonators by a phase bridge system is given

Dual table temperature compensated voltage controlled crystal oscillator system and method

Abstract: Dual table temperature compensation for a voltage controlled crystal oscillator is achieved by sensing the temperature of the voltage controlled crystal oscillator (VCXO), retrieving from a first table the frequency error with variations in the temperature sensed, retrieving from a second table the oscillator control voltage corresponding to the frequency error from the first table and applying the oscillator control voltage to the VCXO.

Utilization of Miniature Multilayer Ceramic Inductors in the Dual-Mode Crystal Oscillator

Abstract: This paper deals with dual-mode crystal oscillator (DMXO) based on two bridge- type oscillators using a quartz resonator as frequency stabilization element and sensor element of its own temperature as well. We have investigated a possibility of miniature multilayer ceramic inductors employment in the DMXO. Employment of such miniature inductors instead of air-core wire-wound ones enables further reduction of the oscillator dimensions, as well as a reduction of temperature gradients among the DMXO elements.

A novel voltage controlled crystal oscillator circuit

Abstract: A novel approach reported in this paper optimizes the dynamic noise and drive sensitivity factor for achieving low phase noise VCXO circuits. An example of mode-feedback and differential coupled crystal oscillators are demonstrated for the validation of this approach, which minimizes the phase noise for inexpensive low quality factor (Q) crystal resonator based oscillators. The noise reduction techniques described in this work offers cost-effective signal source solutions for consumer electronics applications where use of expensive high Q crystal resonator is unaffordable.

Miniaturization and resolution improvement of load sensor using AT-cut quartz crystal resonator

Abstract: A compact load sensor we developed uses an AT-cut quartz crystal resonator whose resonance frequency changes under external load, and features high sensitivity, high-speed response, and a wide measurement range. Also it has the superior feature in the temperature and frequency stability. In the past, the quartz crystal resonator had been hardly applied to the load measurement because of low degree of mechanical characteristic, that is, it is weak to stress concentration by bending. We have developed and characterized a sensor mechanism that safely maintains the quartz crystal resonator. The objective of this study is to improve the resolution of load measurement and to miniaturize the sensor. We designed a novel retention mechanism of the quartz crystal resonator which is fixed vertical to the applied load. The new load sensor was evaluated on the relation between load and resonance frequency as well as temperature and resonance frequency.

An automated system for the precision measurement of the long-term frequency stability of quartz resonators

Abstract: An automated system for the precision measurement of long-term frequency stability, designed for testing quartz resonators during production, is developed. During such tests, the point of inflection of the frequency-temperature characteristic is determined and possible “aging” of the resonator frequency during use is predicted.

Phase noise in detached Crystal Oscillators

Abstract: Progress made in the realization of 5Mhz Crystal Oscillators with “detached” Crystal. Presentation of phase noise measurements made in closed and open loop, which show a behavior which is, compared with conventional precision crystal oscillators, much closer to a plot of an ideal oscillator.

Development of minitype low-power consumption quartz crystal oscillators

Abstract: With the system to an integrated and modularization development, crystal oscillator miniaturization, low power consumption have become increasingly demanding. First, it is required to develop small, low-power crystal oscillator design, to solve the equivalent resistance and lower the chip operating voltage, input current issues. Then the design is verified through the production of crystal samples and testing — a number of typical crystal frequency oscillators are developed with the average power consumption of 1.5mW. Compared with the common crystal oscillators the power consumption has been greatly reduced.

Load capacitance effect on frequency-temperature characteristics of AT-cut quartz crystals

Abstract: The effective frequency-temperature curve of a crystal resonator operated with series load capacitance differs from that of the crystal alone. Since the principal method of compensating for the crystal frequency-temperature behavior in a crystal oscillator employs series varactors and a temperature sensitive compensation network, it is of major importance to be able to understand and deal with this effect in the design of crystal oscillators and crystal resonators assigned in the manufacture of these parts. The necessary formulas and discussions are given in this paper. Mass-loading effects are included and sample charts are provided.

Optimization of dual-mode crystal oscillator

Abstract: This paper deals with dual-mode crystal oscillator (DMXO) based on two modified Butler's oscillators using a quartz resonator as frequency stabilization element and sensor element of its own temperature as well. The main attention is devoted to the amplitude condition of oscillations excitation. This issue was investigated by means of so called regeneration coefficient that was obtained for the treated DMXO. The knowledge of this measure is crucial at the startup of dual-mode oscillations.