Crystal oscillators are also divided into two types: passive crystal oscillators and active crystal oscillators. Passive crystal oscillators are different from active crystal oscillators (resonant) in that passive crystal oscillators are called crystals, while active crystals are called oscillators. The passive crystal oscillator needs to use the clock circuit to generate an oscillation signal, and it cannot oscillate itself, so the term "passive crystal oscillator" is not accurate; An active crystal oscillator is a complete resonant oscillator. Quartz crystal oscillators and quartz crystal resonators are both electronic devices that provide a stable circuit frequency. The quartz crystal oscillator uses the piezoelectric effect of the quartz crystal to vibrate, while the quartz crystal resonator uses the quartz crystal and the built-in IC to work together. The oscillator is directly used in the circuit, and the resonator generally needs to provide 33V voltage to maintain the operation. Oscillators have one more important technical parameter than resonators: resonant resistance (RR), and resonators have no resistance requirements. The size of the RR directly affects the performance of the circuit, so it is an important parameter for various merchants to compete.
The crystal oscillator can be electrically equivalent to a capacitor and a resistor connected in parallel and then connected in series with a capacitor in series, and electrically this network has two resonance points, with the high and low frequency of the frequency, the lower frequency is the series resonance, and the higher frequency is the parallel resonance. Due to the characteristics of the crystal itself, the distance between these two frequencies is quite close, in this extremely narrow frequency range, the crystal oscillator is equivalent to an inductance, so as long as the two ends of the crystal oscillator are connected in parallel with a suitable capacitor, it will form a parallel resonant circuit. This parallel resonant circuit can be added to a negative feedback circuit to form a sine wave oscillation circuit, because the frequency range of the crystal oscillator equivalent to the inductance is very narrow, so even if the parameters of other components change greatly, the frequency of this oscillator will not change greatly. There is an important parameter of the crystal oscillator, that is, the load capacitance value, and the parallel capacitance equal to the load capacitance value can be selected to obtain the nominal resonant frequency of the crystal oscillator. The general crystal oscillation circuit is connected to the crystal oscillator at both ends of an inverting amplifier (note that the amplifier is not an inverter), and then two capacitors are connected to both ends of the crystal oscillator, and the other end of each capacitor is connected to the ground, the capacity value of these two capacitors in series should be equal to the load capacitance, please note that the pins of the general IC have equivalent input capacitors, which cannot be ignored. The load capacitance of a typical crystal oscillator is 15p or 125P, if the equivalent input capacitance of the component pins is considered, then the oscillation circuit with two 22P capacitors forming a crystal oscillator is a better choice.
The crystal oscillator has a piezoelectric effect, that is, the crystal will be deformed after the voltage is applied to the two poles of the wafer, and in turn, if the external force deforms the wafer, the metal sheet on the two poles will generate voltage. If an appropriate alternating voltage is applied to the wafer, the wafer will resonate (the resonant frequency is related to the inclination angle of the quartz bevel, etc., and the frequency is constant). Crystal oscillators use a crystal that converts electrical and mechanical energy into each other, and can provide stable and accurate single-frequency oscillation when operating in a resonant state. Under normal operating conditions, the absolute accuracy of ordinary crystal frequency can reach 50 parts per million. Taking advantage of this feature, the crystal oscillator can provide relatively stable pulses, which are widely used in the clock circuit of microchips. Most of the wafers are made of quartz semiconductor material, and the shell is encapsulated with metal.
Quartz crystal oscillator, also known as quartz resonator, referred to as crystal oscillator, is a resonant device made of the piezoelectric effect of quartz crystal (silicon dioxide crystal), its basic composition is roughly: cut a thin slice from a quartz crystal according to a certain azimuth angle (referred to as a wafer, it can be square, rectangular or round, etc.), coated with a silver layer on its two corresponding surfaces as an electrode, and weld a lead wire to the pin on each electrode, plus the package shell.
When a thin sheet of quartz crystal is subjected to an external alternating electric field, it produces mechanical vibrations, and when the frequency of the alternating electric field is the same as the natural frequency of the quartz crystal, the vibration becomes very strong, which is the reaction of the resonant characteristics of the crystal. Taking advantage of this characteristic, it is possible to replace LC (coil and capacitance) resonant circuits, filters, etc., with quartz resonators. Due to the advantages of small size, light weight, high reliability and high frequency stability, quartz resonators are used in household appliances and communication equipment. Quartz resonators are mainly used as resonant elements in oscillation circuits that require very stable frequency because of their extremely high frequency stability.
SYN5305 crystal oscillator testerIt is a multi-functional crystal oscillator test system independently developed and designed and produced in accordance with the IEC 444 standard, the crystal oscillator tester adopts a 7-inch large touch screen design, the frequency measurement resolution can reach up to 12 bits S, the measured frequency range is up to 6GHz, the load capacitance is arbitrarily adjustable in the range of 5P and 20P, and the internal time base of the host is equipped with high-precision OCXO constant temperature crystal oscillator as standard, and high-stability crystal oscillator and rubidium clock are optional.
When a thin sheet of quartz crystal is subjected to an external alternating electric field, it produces mechanical vibrations, and when the frequency of the alternating electric field is the same as the natural frequency of the quartz crystal, the vibration becomes very strong, which is the reaction of the resonant characteristics of the crystal. Taking advantage of this characteristic, it is possible to replace LC (coil and capacitance) resonant circuits, filters, etc., with quartz resonators. Due to the advantages of small size, light weight, high reliability and high frequency stability, quartz resonators are used in household appliances and communication equipment. Quartz resonators are mainly used as resonant elements in oscillation circuits that require very stable frequency because of their extremely high frequency stability.
Features: High integration, high precision;
Good stability and reliable performance;
7-inch touch screen design, easy to operate.
Typical Applications. Manufacturers of communication equipment, automotive electronics, medical electronics, security electronics, industrial automation equipment, etc., verify or screen crystal oscillators that provide reference frequencies.
Product features. ppm measurement, upper and lower limit measurement;
Frequency measurement range up to 6GHz;
Frequency measurement resolution up to 12-bit s;
A variety of crystal oscillator test fixtures to meet the needs of routine test applications.