46results about How to "High-frequency stability" patented technology

In a method for manufacturing a quartz crystal oscillator, at least one of a chemical etching method, a physical etching method, and a mechanical method is utilized to form a quartz crystal tuning fork resonator having a quartz crystal tuning fork base, quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, a fundamental mode of vibration, and a second overtone mode of vibration each comprised of a flexural mode of an inverse phase. An amplification circuit is provided having at least an amplifier. A feedback circuit is provided having the quartz crystal tuning fork resonator and capacitors. The amplifier of the amplification circuit and the quartz crystal tuning fork resonator and capacitors of the feedback circuit are electrically connected together.

In a method for manufacturing a quartz crystal unit and an electronic apparatus having the quartz crystal unit, each of the quartz crystal unit and the electronic apparatus having the quartz crystal unit, comprising the steps of forming a quartz crystal tuning fork resonator capable of vibrating in a flexural mode of an inverse phase, and having first and second quartz crystal tuning fork tines by etching a quartz crystal wafer; disposing an electrode on each of two of side surfaces of each of the first and second quartz crystal tuning fork tines so that the electrodes on the side surfaces of the first quartz crystal tuning fork tine have an electrical polarity opposite to an electrical polarity of the electrodes on the side surfaces of the second quartz crystal tuning fork tine; mounting the quartz crystal tuning fork resonator on a mounting portion of a case; and connecting a lid to the case to cover an open end thereof, the quartz crystal unit comprising the quartz crystal tuning fork resonator with a piezoelectric constant e′₁₂ within a range of 0.12 C/m² to 0.19 C/m² in the absolute value.

An oscillator includes an oscillation element; an oscillation circuit which causes the oscillation element to oscillate; a heat generation element which heats the oscillation element; a temperature control circuit which controls the heat generation element; and a temperature correction circuit which corrects frequency-temperature characteristics of an output signal of the oscillation circuit.

An integrated semiconductor memory includes a clock generator circuit driven by an external clock signal and a control circuit driven by the external clock signal. The clock generator circuit generates an internal clock signal with a first level if the external clock signal level lies above a sensitivity level of the clock generator circuit for at least the duration of a sensitivity time of the clock generator circuit, and generates the internal clock signal with a second level if the external clock signal level lies below the sensitivity level for at least the duration of the sensitivity time of the clock generator circuit. The control circuit controls the clock generator circuit such that the control circuit selects the sensitivity time of the clock generator circuit in response to characteristics of the external clock signal.

An atomic oscillator includes a gas cell, a semiconductor laser, a light detector, a bias current control section controlling a bias current based on intensity of light detected by the light detector, a memory, and an MPU. The MPU sweeps the bias current and stores a value of the bias current and a value of the intensity of the light when the intensity of the detected light shifts from a decrease to an increase and re-sweeps to set the bias current based on the value of the bias current stored in the memory after the sweep, compares the value of the intensity of the detected light with the value of the intensity of the light stored in the memory while the bias current control section controls the bias current, and determines whether to perform the sweep again in accordance with the comparison.

The invention discloses a double-feedback semiconductor laser frequency stabilization system based on an optical frequency comb. The system carries out the closed-loop feedback control of the frequency of a laser through employing a high-precision wavelength and an acousto-optic modulator. The rough control of a laser output frequency is carried out through a computer and a PID control unit; the laser frequency is shifted by a certain frequency through an acoustic optical modulator and is quickly and accurately controlled, and then the laser frequency is locked in a high-precision and high-stability mode by beating the laser frequency with the optical frequency comb. Finally, the laser with the laser frequency tuned and stabilized serves as pumping laser to be applied to an SERF magnetometer device, the long-term stability of alkali metal atoms pumped by the laser can be guaranteed, so that the detection sensitivity of SERF magnetometer magnetic field measurement is improved. Accordingto the invention, long-term high-precision and high-stability locking of the laser frequency is realized by using the optical frequency comb, and rapid and accurate modulation of the laser frequencycan be realized through constructed double-closed-loop feedback control.

A clock generating device measures a frequency ratio between a clock signal (32.768 kHz+α) and a reference frequency value based on a clock signal (25 MHz); generates a clock signal obtained by masking a portion of clocks of the clock signal based on a measurement result of the frequency ratio; and updates a compensation value of a frequency temperature characteristic of the clock signal when a difference between the measurement result of the frequency ratio and an average value of N (N is a natural number) measurement results is greater than a reference value of the frequency ratio.

A phase shifting method and a phase shifter are provided. The phase shifter comprises a first (200) and a second (202) transmission line structure in parallel, the structures having a common input, each structure comprising cascaded forward and backward transmission lines and the same number of components. The component values of the second structure are equal to the component values of the first structure multiplied by a given proportionality constant.

It is an object of the present invention to provide a PLL apparatus realizing extremely high frequency stability.

As a concrete means for solving the problem, an A/D (analog/digital) conversion unit samples a standard signal based on a 40 MHz frequency signal, which is a rectangular wave, from an oven-controlled crystal oscillator (OCXO), and an orthogonal transformation unit applies orthogonal transformation to a digital signal from the A/D conversion unit to extract a real part (I) and an imaginary part (Q) which are complex expression of a phase vector equivalent to a phase difference between the standard signal and the frequency signal from the OCXO. An angular velocity of this vector is detected and a direct-current voltage according to the angular velocity is generated and supplied to the OCXO via a PWM control unit.