Quartz resonator is a component that calculates the operating frequency, so the stability of its own frequency is very important. If the frequency is unstable, the signal provided is wrong, which will affect the correct performance of the component and malfunction. So, how to improve the frequency stability of the quartz resonator?

    What are the main factors that affect the frequency stability of quartz crystal resonators in the first place:

    1, temperature

    The ambient temperature of a quartz resonator is the main factor that affects its frequency change. The resonance frequency will change with the temperature. This characteristic is called the frequency temperature characteristic. In addition to its own physical characteristics, this characteristic of the quartz resonator has a certain relationship with its cutting angle and processing flow. Constant temperature and temperature compensated oscillators are developed based on frequency and temperature characteristics.

    2, aging

    Aging is a physical reason that affects the normal operation of many components. The quartz resonator will gradually decrease or increase with time. Specifically, the aging of the quartz resonance can be explained from the following aspects.

    (1) The imperfection of the quartz crystal lattice inside the resonator causes the structure of the crystal to change during operation. This is a long-term effect: in addition, the decomposition and absorption of gas causes the quality or migration of the plate, and the effect will last for weeks or years ;

    (2) aging due to temperature gradient effects;

    (3) Aging occurs due to the pressure release effect, which is a function of the temperature gradient effect process and generally lasts for several months.

    (4) Change of excitation level. Research shows that the excitation level has a significant effect on the resonant frequency of the crystal oscillator; if the excitation current is too large or too small, it will affect the aging performance of the quartz crystal and the long-term or short-term stability of the resonant frequency, so whether the excitation level Stability directly affects the frequency stability of the quartz crystal resonator.

    In addition, changes in load, fluctuations in power supply voltage, and nuclear radiation will also cause the resonance frequency of the quartz crystal resonator to change. When quartz crystal resonators are used in certain occasions with high precision requirements, the influence of these factors on the resonant frequency of the resonator cannot be ignored.

    方法 Quartz resonator frequency stability improvement method:

    1. In addition to a good crystal circuit, measures must be taken to reduce the influence of external temperature on the oscillation frequency. In the circuit of the temperature-compensated quartz oscillator, a varactor diode is connected in series with the quartz crystal. When the external temperature changes, the capacitance of the varactor diode changes, so that the resonance frequency of the quartz crystal changes with the temperature in the opposite direction to reduce the temperature. Effect on the oscillation frequency.

    2. The aging effect of quartz crystal is a phenomenon that its resonance frequency changes slowly with time. Although the quartz crystal has undergone aging treatment by the manufacturer, it must be used after tens of days, or the frequency compensation capacitor must be adjusted to make the oscillator work at the specified frequency.

    3. When the quartz crystal works, the excitation voltage is applied at both ends, which consumes a certain amount of power. If the excitation voltage is too high, the thermal effect caused by the loss will be too large, which will cause the resonance frequency to change, produce irreversible aging drift, or make the vibration amplitude of the wafer too large, which may even cause the wafer to crack and damage. Too small excitation voltage will make the oscillator The output is reduced, and even the oscillation cannot be maintained. To stabilize the frequency of the quartz resonator, the excitation level must be appropriate and stable.