Showing papers on "Crystal oven published in 1999"

Apparatus for detecting hydrocarbons using crystal oscillators within fuel dispensers

Abstract: A vapor recovery system (18) utilizes a crystal oscillator (30) for sensing the presence of hydrocarbon in the vapor emissions emanating from a fuel tank (10) during refueling. The crystal oscillator (30) is coated with a layer of material having a sensitivity for hydrocarbon. In response to any interaction between the coating layer and hydrocarbon, the crystal oscillator (30) experiences a shift in its oscillation frequency relative to the fundamental resonance frequency. The frequency shift (34) is representative of the hydrocarbon concentration in the vapor emissions. A control signal (36) based on the frequency shift (34) is generated and then used to adjust the operating speed of a vapor pump (26).

Solving the cable problem between crystal sensor and electronics by use of a balanced bridge oscillator circuit

Abstract: The balanced bridge oscillator circuit presented here perfectly compensates for the negative influence of the cable. The oscillator circuit is characterized by two almost equal bridge branches; the first one contains the sensor crystal connected via the sensor cable, the second one contains an identical cable terminated by a capacity equal to the resonator's static capacity C/sub 0/. The cable compensation performance of the balanced bridge oscillator has been justified by a respective circuit analysis and by measurements of its key specifications in comparison with those of a conventional oscillator.

A universal 0.03-mm/sup 2/ one-pin crystal oscillator in CMOS

Abstract: A one-pin crystal oscillator with an integrated load capacitance of 15 pF has been realized in a standard 0.35-/spl mu/m CMOS technology. Due to the structure of the oscillator and the use of MOS gate capacitance for the load capacitors, the chip area can be very small. The total active area including load capacitors is less than 0.03 mm/sup 2/. The design can be operated with supply voltages in the range of 1.4-3.6 V and allows crystal frequencies in the range of 3-30 MHz. The current consumption of the oscillator core is 180 /spl mu/A at 10 MHz with 3.3-V power supply. It produces a rail-to-rail output swing, regulated by an amplitude control loop, and has the same flexibility and ease of frequency tuning as a common Pierce oscillator. As no special IC process options are required, the design is very suitable for clock generation in digital very-large-scale-integration chips.

Crystal resonant frequency sensor

Abstract: A method and apparatus for measuring the frequency of a desired resonant mode of a crystal arrangement, or other two-port device, during an automated operation. The crystal arrangement, or other two-port device, is placed into a test circuit and subjected to a sinusoidal test signal of known frequency. Based upon the output response of the crystal arrangement to the test signal, the frequency of the test signal is changed such that the test signal rapidly converges on a desired mode of operation of the crystal arrangement. This is accomplished by first noting a desired increase in amplitude of the output response of the crystal arrangement, followed by measuring an error signal related to the desired crystal arrangement mode of operation. When the error equals a predetermined value the frequency of the sinusoidal test signal is the frequency of the desired mode.

Crystal oscillator and drive characteristic measuring method for quartz oscillator in the same

Abstract: PROBLEM TO BE SOLVED: To stably and precisely measure a drive characteristic even after a quartz oscillator is loaded on an oscillator SOLUTION: An oscillation circuit part 12 is constituted of the DLD characteristic measuring circuit part 13 of a quartz oscillator, which is surrounded by an illustrated broken line, an active oscillator 14 formed of a transistor, which is for driving a quartz oscillator 11, and a function circuit 15 (burr cap capacitor in the case of VCXO and temperature compensation circuit in the case of TCXO) for adjusting and controlling a frequency The DLD characteristic measuring circuit part 13 is constituted of a crystal current control circuit 13a controlling crystal current and varying the drive level of the crystal oscillator 11 and a variable resistor 13b connected in series to the quartz oscillator 11

Device at piezoelectric crystal oscillator

Abstract: The present invention offers a monolithic, piezoelectric crystal device which simultaneously (i) has several oscillators on the same crystal, the resonance frequencies of which can be selected in a flexible way; (ii) does not show any problem with regard to acoustic superhearing between the oscillators, and (iii) facilitates a simple addressing of the single oscillators.

Driving method of liquid crystal panel, liquid crystal device, and electronic equipment

Abstract: PROBLEM TO BE SOLVED: To provide a driving method of a liquid crystal panel in which driving conditions can be optimized by performing temperature compensation without varying a driving signal voltage, and to provide a liquid crystal device, and electronic equipment using this liquid crystal device. SOLUTION: The liquid crystal device 1 is temperature-compensated so that, based on the temperature detection result by a temperature detector 70, a temperature compensation circuit 80 operates almost under a flat condition of dielectric constant anisotropy Δe of liquid crystal by lowering a frame frequency of a driving signal outputted to the liquid crystal panel 10 from driving circuits 20, 30 on the low temperature side. Moreover, the temperature compensation circuit 80 increases the frame frequency of the driving signal corresponding to the fact that the motion of liquid crystal molecules is more activated on the side of high temperatures. However, 50 Hz (or 60 Hz) and its multiples are avoided for the frame frequency. COPYRIGHT: (C)2001,JPO

Fundamental mode 155 MHz with flat blank in the crystal unit using VCXO

Abstract: Fundamental mode At-cut 155.52 MHz crystal units are used in the VCXO (Voltage Controlled Crystal Oscillator) for the base station. To this oscillator, both high frequency stability and wide frequency trim range are required. One of the solutions is to use flat wafer, which are used in 10 MHz, 20 MHz and etc. crystal units. Because the thickness of AT-cut 155.52 MHz blank is about 10-micron meter, to realize make such thin blank is about 10-micron meter, to realize make such thin blank, it is necessary to review and use method of the wafer. Also it is necessary to study blank protection against external shock. This paper shows the results of these above and oscillator's frequency stability. At first, lapping method of this wafer is discussed. Next, as an applied examples, fundamental mode AT-CUT 155.52 MHz, drive level characteristics, temperature characteristics, equivalent characteristics are discussed. Also as further step applied example, crystal oscillator's temperature characteristics, and long term frequency stability are shown.

A stable oscillator circuit for generators with direct temperature controlled crystal unit

Abstract: Investigation results are presented of an oscillator circuit with SC-cut quartz resonator characterized by low frequency drift due to environmental conditions. With this simple circuit C-mode excitation is possible without frequency selective networks. The circuit is intended for generators based on direct temperature control and can be utilized also in thermocompensated oscillators.

Method of initializing an oscillator circuit

Abstract: A programmable crystal oscillator is provided having a memory for storing frequency-defining parameters. Typically, one of these parameters is used to program an adjustable capacitive load circuit coupled to a crystal to thereby adjust the crystal source frequency. Additional parameters are used to program the output frequency of a phase locked loop circuit coupled to receive the adjusted source frequency. A further parameter can also be used to divide the output frequency of the phase locked loop circuit to supply a specified output frequency. The oscillators can be manufactured as generic programmable crystal oscillators without regard for output frequency and then quickly programmed to produce customer-specified output frequencies with a high degree of accuracy.

Thermal regulation of double oven controlled crystal oscillator, DOCXO

Abstract: The presentation will discuss the differences and advantages of a thermal regulating system using the integral proportional method. The design study compares the results with a double oven controlled crystal oven using a simple integral thermal regulation. The obtained results using the described method show considerable improvement of frequency stability with temperature and the warm up time is much reduced : -20/spl deg/C+70/spl deg/C<1.10/sup -10/ 10 min <5.10/sup -10/ The holder size is also reduced to 50/spl times/50/spl times/38 mm. The simple proportional regulation method very much depends on the external conditions and the various thermal losses of the mass to be thermally regulated. Effectively this method is used to compensate for thermal losses of the system. The proportional integrated method overcomes the problem and is therefore more suitable for high stability oscillators. The principal problem to resolve is to understand and control the oven thermal constants as a function of the time constants of the integration.

A VHF low phase noise crystal oscillator

Abstract: Based on the principles of designing a low phase noise crystal oscillator, the authors present a crystal oscillator circuit with two or three crystals. The electronic and mechanical construction of a crystal oscillator, EMC design, and how to choose suitable components are also mentioned. Based on this kind of circuit, a type of 100 MHz crystal oscillator with low phase noise (#(100 kHz)=-178 dBc/Hz) was developed by the authors. It can work in a very wide temperature range, which is from -55/spl deg/C -75/spl deg/C. It is suitable for mass production instead of just being developed in a laboratory.

Drive-level dependence of long-term aging in quartz resonators

Abstract: To analyze the factors of frequency aging in ultra-stable quartz crystal oscillators, a novel system that continuously measures the stability in both resonant frequencies of the resonators and oscillation frequencies has been proposed. Experimental results show that the long-term drift of resonant frequency depends mainly on the amplitude of the crystal driving current and that the aging of the circuit partly affects the aging of oscillation frequency.

Fuzzy control based frequency synchronization using GPS carrier phase measurements

Abstract: Frequency synchronization using GPS carrier phase measurements based on fuzzy controller is presented. The frequency offset of the remote OCXO (Oven-Controlled Crystal Oscillator) with respect to the primary atomic clock is precisely estimated in real time by performing the GPS carrier phase single-difference and time-difference. Through the D/A converter, the remote clock is then steered to synchronize with the master clock. The accuracy of the remote clock can be improved from about 5/spl times/10/sup -9/ to about 1/spl times/10/sup -13/. Moreover, a new methodology of frequency transfer by performing carrier phase single-difference without resolving the carrier phase cycle ambiguity is discussed. The zero-baseline tests with common high-performance cesium clock show that the methodology we proposed has a frequency uncertainty of 5 parts in 10/sup 16/ for averaging times of one day.

Statistical results from high volume production of ultra stable precision quartz oscillators

Abstract: Statistical results from a sample of greater than 10,000 5 MHz 260 Series oscillators, designed and developed as an alternative to Rubidium oscillators by MTI-Milliren Technologies, Inc., confirm successful high volume production of this ultra-stable oversized crystal oscillator. Results from various performance parameters including thermal stability, aging, phase noise, and short-term stability are presented.

Frequency jump characteristics versus temperature changes in AT- cut bar oscillators

Abstract: An analysis of frequency jump and series arm resistance for an AT-cut bar oscillator taking electrode film thicknesses into account was conducted using the electric equivalent circuit model. To test it frequency and resistance characteristics versus temperature changes in AT-cut bar oscillators and resonators were measured taking electrode film thicknesses into account.