what is the crystal oscillator circuit ？
what is the crystal oscillator circuit ？
A crystal oscillator circuit is a type of circuit that generates an oscillating current with a period.
It is commonly used in electronic devices to provide a stable and precise frequency reference.
LC crystal oscillator circuit
The most basic type of crystal oscillator circuit is the LC oscillator circuit, which is also known as a resonant circuit, tank circuit, or tuning circuit. This circuit consists of an inductor (L) and a capacitor (C) connected together.
The LC oscillator circuit operates by storing energy in the electric and magnetic fields of the inductor and capacitor, and then transferring this energy back and forth between them. The frequency of oscillation is determined by the values of L and C, and can be calculated using the formula f = 1/(2π√(LC)).
In some cases, more complex crystal oscillator circuits may be used to generate higher frequencies or to provide additional features such as frequency modulation. However, regardless of the specific design, all crystal oscillator circuits operate on the same basic principle of using the oscillating energy stored in an LC circuit to generate a stable and precise frequency reference.
Equivalent circuit
Equivalence in circuit analysis refers to the process of replacing a complex circuit with a simpler circuit that has the same overall behavior on the rest of the circuit or external components. This simplification technique enables engineers to analyze and understand the behavior of the circuit more easily.
Quartz crystal equivalent circuit：The equivalent circuit of a quartz crystal can be represented as a flat capacitor Co when the crystal is not vibrating. This capacitor is also known as an electrostatic capacitor and is determined by the geometric size of the crystal and the electrode area.
Quartz crystal equivalent circuit：
the equivalent circuit of quartz crystal: When the crystal does not vibrate, it can be seen as a flat capacitor Co,
called an electrostatic capacitor. Co is related to the geometric size of the chip and the electrode area.
1.The "Co" symbol represents the sum of static capacitance and distributed capacitance such as support leads, typically around 2-5PF.
2.The symbol 'Cq' represents a dynamic capacitance that characterizes the elasticity of the crystal, with a small value below 10-pF.
3.The "Lq" symbol represents the dynamic inductance, representing the quality of the crystal, with a large value ranging from tens of mH to hundreds of H.
4.The symbol 'rq' represents the loss caused by dynamic resistance, mechanical friction, and air damping, with a small impedance ranging from a few to a few hundred ohms.
5.The symbols "Lq1, Cq1, rq3" represent the equivalent circuit of the crystal fundamental frequency.
6.The symbols "CLq3, Lq3, rq3" represent the equivalent circuit of crystal third overtone.
Parallel connection of quartz crystal oscillator circuit:
Series connection of quartz crystal oscillatior circuit
Why is it usually necessary to add two resonant capacitors CL1 and CL2?
What is inside crystal oscillator