Oscillator device

Patent metadata

Field	Value
Publication number	US-10992260-B2
Application number	US-201916981706-A
Country	US
Kind code	B2
Filing date	Mar 25, 2019
Priority date	Mar 26, 2018
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

In an oscillator device that outputs a frequency signal based on an oscillation frequency of a crystal resonator and a frequency setting value, a frequency difference detector that obtains a difference value corresponding to a frequency difference between the output frequency of the oscillator device and an external clock signal and a temperature detector are disposed. An aging coefficient and a temperature characteristic coefficient are obtained based on a secular change of the difference value obtained in the frequency difference detector and a secular change of the detected temperature during a period where the external clock signal is obtained. Furthermore, a frequency correction value is calculated using the aging coefficient and the temperature characteristic coefficient during a holdover period, and the frequency correction value is added to the frequency setting value.

First claim

The invention claimed is:

1. An oscillator device comprising:
an oscillating unit that includes a crystal resonator to output a frequency signal based on a frequency setting value;
a frequency difference detector that obtains a difference value corresponding to a frequency difference between an external clock signal obtained from outside and a frequency signal output from the oscillating unit;
a temperature detector that detects a temperature of an atmosphere where the crystal resonator is disposed;
a correction value calculator that calculates a frequency correction value to be added to the frequency setting value in order to equalize a frequency of the frequency signal to the frequency corresponding to the frequency setting value;
an addition unit that adds the frequency correction value obtained from the correction value calculator to the frequency setting value input to the oscillating unit; and
a correction coefficient calculator that calculates an aging coefficient and a temperature characteristic coefficient based on a secular change of the difference value obtained in the frequency difference detector and a secular change of the detected temperature detected in the temperature detector, the aging coefficient indicating a changing rate of the frequency correction value per unit time, the temperature characteristic coefficient indicating a changing rate of the frequency correction value per unit temperature, wherein
the correction value calculator calculates the frequency correction value based on the difference value detected in the frequency difference detector during a period where the external clock signal is obtained, and calculates the frequency correction value using the aging coefficient and the temperature characteristic coefficient during a period where the external clock signal is interrupted.

2. The oscillator device according to claim 1 , wherein
the oscillating unit includes a PLL circuit unit including a voltage control oscillator and a DDS that outputs a frequency signal for reference for the PLL circuit unit corresponding to the frequency setting value by receiving the frequency setting value and a reference clock, and
the crystal resonator is disposed in an oscillator circuit that outputs the reference clock for the DDS.

3. The oscillator device according to claim 1 , wherein
the oscillating unit includes an oscillator circuit including the crystal resonator.

4. The oscillator device according to claim 1 , further comprising:
a heater unit that heats the atmosphere where the crystal resonator is disposed; and
a heater control unit that adjusts an output of the heater unit such that the temperature detected in the temperature detector becomes a target temperature set in advance.

5. The oscillator device according to claim 1 , wherein
a frequency change rate of the frequency signal with respect to the frequency corresponding to the frequency setting value is 1 ppt/second or less.

6. The oscillator device according to claim 1 , wherein
the correction coefficient calculator calculates the aging coefficient based on an amount of change of the frequency correction value during an aging measurement period that is a period where the changing rate of the detected temperature within a preliminarily set period is equal to or less than a minimum temperature change rate set in advance.

7. The oscillator device according to claim 6 , wherein
the correction coefficient calculator calculates the temperature characteristic coefficient based on a temperature change factor frequency correction amount, the temperature change factor frequency correction amount being a value obtained by subtracting the aging factor frequency correction amount from the amount of change of the frequency correction value during a temperature characteristic measurement period where the changing rate of the detected temperature is larger than the minimum temperature change rate, the aging factor frequency correction amount being obtained based on an aging coefficient calculated in an aging measurement period before a start of the temperature characteristic measurement period and an elapsed time of the temperature characteristic measurement period.

8. The oscillator device according to claim 1 , wherein
the correction coefficient calculator obtains a plurality of the aging coefficients and a plurality of the temperature characteristic coefficients by repeating calculations of the aging coefficient and the temperature characteristic coefficient along an elapse of time, and the correction value calculator calculates the frequency correction value based on an average value of the plurality of aging coefficients and an average value of the plurality of temperature characteristic coefficients.

9. The oscillator device according to claim 1 , further comprising:
a temperature control mechanism for changing the temperature of the atmosphere where the crystal resonator is disposed, wherein
the temperature control mechanism changes the temperature of the atmosphere where the crystal resonator is disposed during a period where the secular change of the difference value and the secular change of the detected temperature are obtained for calculating the temperature characteristic coefficient in the correction coefficient calculator.

Assignees

• Nihon Dempa Kogyo Co

Inventors

• Kobata Tsukasa

Classifications

• H04W56/00 Primary

  Synchronisation arrangements · CPC title

• H03L1/026

  by using a memory for digitally storing correction values (H03L1/025 takes precedence) · CPC title

• H03L1/02

  against variations of temperature only · CPC title

• H03L7/099

  concerning mainly the controlled oscillator of the loop · CPC title

• H03C1/62

  Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present (H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence) · CPC title