Showing papers on "Crystal oven published in 1990"

Low power temperature-controlled frequency-stabilized oscillator

Abstract: A quartz crystal resonator is situated in an enclosure whose interior is substantially a vacuum. A heating element is attached to the crystal surface. A sensor is attached to the crystal enclosure, and may be sandwiched between the crystal enclosure and the circuit board to which the crystal enclosure is attached. A control system converts the sensed temperature into a series of variable width pulses applied to the resonator heating element. Thus, the sensor, control unit and heating element comprise a temperature feedback control system which allows the crystal to operate at or very near its desired temperature. Further, the crystal enclosure may be substantially surrounded by an external material insulator. The external material insulator maximizes thermal resistance between the sensor and the environment in comparison to the thermal resistance between the crystal and the sensor. This choice of relative thermal resistances enables the temperature feedback control system to more closely emulate a closed-loop system possessing the advantages of accuracy and responsiveness. In an especially preferred embodiment, an integrated circuit from a switching power supply may be used in a novel manner to perform certain of the functions in the temperature feedback control loop.

An analysis of oscillation frequency characteristics in a CMOS oscillating circuit using a coupling quartz crystal resonator

Abstract: Oscillation frequency characteristics in a CMOS oscillating circuit using a coupling quartz crystal resonator are described. A miniaturized GT cut quartz crystal resonator consisting of the vibrational portion and the supporting portions which is formed by an etching method is used. The relationship of the resonator's frequency temperature behavior versus load capacitance (CL) is clarified. The oscillating circuit is shown as an electric equivalent circuit. An amplitude continuation condition and an oscillation condition are theoretically derived. The coupling between both vibrations of a coupling quartz crystal resonator is regarded as a capacitive coupling. From the equivalent circuit of the coupling quartz crystal resonator, an imaginary part is easily calculated. As a result, a frequency equation which is given as a function of CL is readily derived from the oscillation condition and the imaginary part of the coupling resonator. It is shown that by suitably choosing CL, the frequency deviation in this CMOS oscillating circuit is less than 1 p.p.m. over a wide temperature range of -30 degrees C to +70 degrees C without any temperature compensation. >

Circuit for preventing VCXO mode jumping

Abstract: An oscillator includes a mechanical resonator, such as a crystal, and having an amplifier arranged for oscillating at a first frequency. A resonant circuit is coupled in series with the crystal. The resonant circuit is antiresonant at an undesired harmonic frequency of the crystal thus prohibiting oscillation of the oscillator at said undesired harmonic frequency. The present oscillator is a portion of a phase locked loop used in a television receiver for demodulating a composite stereophonic audio signal.

Overtone crystal oscillator having resonance amplifier in feedback path

Abstract: In an overtone crystal oscillator comprising a crystal oscillator having a feedback loop and a resonance amplifier whose amplitude characteristic has an overshoot in the range of the resonant frequency of the resonance amplifier and which is arranged in the feedback loop of the crystal oscillator, the resonant frequency of the resonance amplifier is between the frequency of the overtone to be generated and the next lower oscillation frequency of the crystal oscillator, while signals in the frequency range of the next lower oscillation frequency(ies) in relation to signals in the frequency range of the overtone to be generated in the feedback loop, particularly in the resonance amplifier, have such a phase shift that the overtone crystal oscillator cannot oscillate at the frequencies of the next lower oscillation frequency(ies) and that it only oscillates at the frequency of the overtone to be generated.

Electronically controlled oscillator

Abstract: An electronically controlled oscillator capable of operating in the rf/microwave frequency range includes an amplifier (21) having a stacked crystal filter (25) and an electronically variable impedance (26), such as a hyperabrupt junction varactor, connected in a feedback loop to vary the oscillator output frequency about the frequency of the stacked crystal filter. In a further implementation of the oscillator, an overmoded stacked crystal filter (55) is utilized which has a comb response, and a second delay stacked crystal filter (60) is also employed in the feedback path for providing an adjustable phase delay for causing the oscillator to controllably operate at the respective responses in the comb of responses of the overmoded stacked crystal filter.

Temperature stabilized crystal oscillator

Abstract: An electronic circuit including a frequency-selective part including a piezoelectric crystal and an inductance; The crystal is shaped relative to its crystal axes in such a way that its temperature coefficient and the temperature coefficient of the inductance have opposite signs in order to reduce the influence temperature on the pulling range of the frequency-selective part of the circuit.

Vibration analysis of new shape G-type quartz crystal resonator formed by etching method

Abstract: The frequency temperature behavior and electrical characteristics of a novel G-type quartz crystal resonator, formed by an etching method, are described. An objective of the present research is to provide a miniaturized quartz crystal resonator with a frequency of approximately 1 MHz. A novel shaped G-type portion and supporting portions is proposed, and its resonator frequency constant, frequency temperature behavior, and electrical characteristics are theoretically and experimentally clarified in order to realize a miniaturized quartz crystal resonator with a zero temperature coefficient and good electrical characteristics. >

Harmonic crystal oscillator

Abstract: In a harmonic crystal oscillator comprising a crystal oscillator which has a feedback loop, and a resonant amplifier, it is provided that the resonant amplifier is connected into the feedback loop of the crystal oscillator, that the resonant frequency of the resonant amplifier is between the frequency of the harmonic to be generated and the next-lower frequency of oscillation of the crystal oscillator and that signals within the frequency range of the next-lower frequency of oscillation receive a phase shift by about 180 DEG in the resonant amplifier in relation to signals within the frequency range of the harmonic to be generated. … …

Circuit arrangement for the compensation of the frequency change with the temperature of a quarz oscillator.

Abstract: A circuit arrangement for compensating for the change in frequency with temperature of a crystal oscillator, containing a temperature sensor which is thermally coupled to the oscillating crystal, followed by a circuit for simulating the frequency/temperature characteristic of the oscillating crystal, and a circuit connection from the output of this circuit to an input of the crystal oscillator which influences its frequency, the circuit (5) for simulating the frequency/temperature characteristic consisting of a first assembly (7) for simulating the linear component of the characteristic, a second assembly (8) for simulating the non-linear component of the characteristic and a third assembly (9) for superimposing the two components.