What Is a Quartz Oscillator?

Quartz resonator refers to a device made by using the principle that the chip generates a resonance phenomenon due to the piezoelectric effect when the frequency of the electrical signal is equal to the natural frequency of the quartz chip. It is a key component of crystal oscillators and narrowband filters.

When the electrical signal frequency is equal to the natural frequency of the quartz wafer (or rod)

Quartz resonators are commonly used in wafer, rod, and tuning fork types.

The tuning fork type quartz resonator has a small volume, good shock resistance and low frequency. Its resonance frequency is 32.768kHz, which is suitable for use in quartz watches. Recently, many quartz clocks have also adopted such low-frequency quartz resonators.

The wafer type is a high-frequency quartz resonator with a resonance frequency of 4.194304 MHz, which is mostly used for quartz clocks.

Rod-shaped quartz resonators are not suitable for the needs of miniaturized quartz watches because of their poor impact resistance and large size.

At present, tuning fork-type quartz resonators are produced in large quantities, and the vibration of the quartz tuning fork belongs to a bending vibration mode. The fork arm is fixed at one end and freely bends and vibrates at one end, and its frequency is 0.16 times that of free bending vibration at both ends.

Characteristics of several quartz resonators

Serial number	characteristic	symbol	unit	standard value
				+ 5 ° X tuning fork	NT tuning fork	AT wafer
1 2 3 4 5 6 7	Standard frequency Equivalent inductance Equivalent resistance Equivalent capacitance Static capacitance Load capacitance Excitation level	f L 1 R 1 C 1 C 0 C 1 P	Hz H k PF PF PF W	32768 8700 35 0.0027 1.7 13 1	32768 118000 350 0.0002 0.2 2 0.2	4194304 0.38 40 0.0038 3 twenty one 200
8	Quality factor	Q	-	75000	7000	> 250000
9	Zero frequency temperature	T 0		25 ° ± 5 °	25 ° ± 5 °
10 11 12	range of working temperature Storage temperature range Insulation resistance	- - -	M	-10 + 60 -30 + 70 100

In 1921, it was found that the resonance characteristics of quartz wafers had a frequency stabilization effect, and pioneered the application of quartz resonators in communication technology. During the Second World War, piezoelectric quartz technology was greatly developed due to the need for military communications ^[2]

Cutting type In the crystal coordinate system, the cutting of a wafer along a certain direction is called a cutting type. Only certain cut shapes have piezoelectric effect, single vibration mode and zero temperature coefficient, so when designing a resonator, you must first choose a suitable cut shape.

An important way to improve the frequency stability of the quartz resonator is to reduce the influence of the ambient temperature on the frequency. There are usually two approaches.

Constant temperature tank method: Put the resonator in the constant temperature tank. As long as the temperature of the constant temperature tank is consistent with the temperature of the zero temperature coefficient point (T0), the frequency change with temperature will be close to zero.

Temperature compensation method: The frequency change caused by the ambient temperature is compensated by the thermal network. The latter method has the advantages of small size, low power consumption, and can work immediately after starting. The disadvantage is that the frequency stability is lower than the previous method.