Temperature Compensated Crystal Oscillator Is Also One of The Quartz Crystal Oscillators, Referred to as “temperature Compensated Crystal Oscillator“

What are the characteristics of temperature compensated crystal oscillator? Because electronic products in different fields have different demands for quartz crystal oscillators, temperature-compensated crystal oscillators were developed to compensate for the instability of ordinary crystal oscillators at high temperatures. However, temperature-compensated crystal oscillators have There are many types of temperature compensated crystal oscillators, each with its characteristics.

The temperature compensated crystal oscillator consists of a constant temperature bath control circuit and an oscillation circuit. Temperature control is usually accomplished by a differential series amplifier consisting of a thermistor "bridge". The crystal resonator is integrated with the oscillator circuit and does not have temperature compensation and temperature control, which are characteristics of these aspects.

Fig.1

A crystal oscillator is a crystal oscillator in which a varactor diode is inserted in series in a crystal resonator. The capacity of the diode changes according to the external voltage, so that the output frequency can be changed according to the load capacitance characteristics of the crystal resonator. The temperature compensated crystal oscillator is also one of the quartz crystal oscillators (referred to as crystal oscillator).

The accuracy and stability of the temperature compensated crystal oscillator are higher than that of ordinary quartz crystal oscillators, and it can play a role in temperature compensation for the frequency of the crystal oscillator. For example, in some high-temperature environments, some products may suffer from adverse phenomena due to high temperatures, or even cause the entire product to become paralyzed.

In this case, a TCXO will be used to preheat the crystal. The principle is to control the output frequency of the crystal oscillator by sensing the ambient temperature, and appropriately converting the temperature information, thereby achieving the effect of stabilizing the output frequency. Temperature compensated crystal oscillators can supplement weather temperature changes. When the temperature is low, it will compensate for the oscillation frequency deviation caused by changes in surrounding temperature according to its temperature compensation circuit, thereby protecting the stability of the product.

TCXO temperature compensated quartz crystal oscillator is a quartz crystal oscillator that uses an additional temperature compensation circuit to reduce changes in oscillation frequency caused by changes in ambient temperature.

Because electronic products in different fields have different requirements for quartz crystal oscillators, warm-mounted crystal oscillators were developed to compensate for the instability of ordinary crystal oscillators at high temperatures. However, there are many types of warm-mounted crystal oscillators, each of which Each type of warm-mounted crystal oscillator has its own characteristics.

Fig.2

The temperature compensated crystal oscillator consists of a voltage controlled crystal oscillator (VCXO) and a temperature compensated crystal oscillator (TCXO). The voltage-controlled crystal oscillator adds the modulation signal to the varactor diode through the modulation terminal of the crystal oscillator, so that the frequency of the crystal oscillator changes with the amplitude of the modulation signal, thereby achieving the purpose of frequency modulation.

Crystal oscillators have more advantages in temperature and frequency stability. TCXO mainly uses the attached temperature compensation circuit to reduce the impact of ambient temperature on the oscillation frequency. Temperature compensation includes direct compensation and indirect compensation. Indirect compensation can be divided into analog and digital forms.