Oven controlled crystal oscillator

Abstract

An oven controlled crystal oscillator includes a crystal oscillator, a temperature control circuit, and a control integrated circuit. The crystal oscillator includes a crystal resonator and an oscillator circuit. The temperature control circuit includes a heater resistor, a thermistor, a first resistor, a second resistor, a third resistor, a differential amplifier, a thermosensor, and a fourth resistor. The thermosensor is disposed in parallel to the first resistor. The thermosensor has one end to which the supply voltage is supplied. The fourth resistor has one end connected to another end of the thermosensor and another end that is grounded. The control integrated circuit includes a digital variable resistor and a controller. The digital variable resistor is connected to the thermosensor in parallel. The controller adjusts a resistance value of the digital variable resistor based on a digital control signal input from outside.

Description

technical field [0001] The present invention relates to a crystal oscillator with a constant temperature bath, and more particularly to a crystal oscillator with a constant temperature bath that can perform frequency adjustment with high precision and easily without deteriorating phase noise characteristics. Background technique [0002] [Description of Prior Art] [0003] The Oven Controlled Crystal Oscillator (OCXO) is a structure in which the crystal oscillator is stored in an oven (oven) and maintained at a constant temperature, and it has high frequency stability even among crystal oscillators. [0004] The oven is equipped with a temperature sensor and a heat source, and the temperature is controlled so as to keep the inside at a constant temperature. [0005] In OCXO, a vibrator designed exclusively for OCXO is used, represented by SC cut or AT cut. The frequency-temperature characteristic of the AT-cut vibrator is a cubic function curve, and the temperature is cont...

AI Technical Summary

Problems solved by technology

[0023] However, in the conventional crystal oscillator with a constant temperature bath, it is necessary to manually adjust the temperature control circuit and the oscillator for each product, and the work is cumbersome. In addition, in the oscillator using the PLL circuit, there is a frequency adjustment that is easy but difficult. Problems where phase noise will degrade

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