In order to facilitate the subsequent analysis of the load capacitance to the frequency and start-up of the crystal oscillator manufacturer, the real part Re and the imaginary part of the complex impedance of the crystal oscillator in the formula XePierce crystal oscillator manufacturer are a modification of the Colpits capacitor three-point crystal oscillator manufacturer. , It can work in the frequency range of several kHz to several hundred MHz. Because of its simple structure, low cost, high precision, good waveform, especially low power consumption and insensitive to factors such as power supply voltage and ambient temperature, it is in engineering It is widely used in practice, especially in digital integrated circuits. The clock circuits of most chips have adopted Pierce crystal oscillator manufacturers. The circuit principle of the crystal oscillator manufacturer is mainly composed of inverter Inv, feedback resistance RF, crystal oscillator JT and capacitors C1 and C2. The function of the feedback resistor is to make the inverter function equivalent to the amplifier by introducing feedback. The feedback resistor makes the amplifier bias when the output voltage is equal to the input voltage, forcing the inverter to work in the linear region. The feedback resistor and the inverter are usually integrated Inside the chip. The external crystal oscillator and 2 capacitors form a frequency selection loop.

(A) In the AC equivalent circuit shown, the inverting amplifier is equivalent to a controlled current source, the control voltage is the feedback voltage VI, and the transconductance is gm; the crystal oscillator adopts the impedance form given by the formula. Firstly, the closed-loop phase analysis method is used to determine the voltage, current and impedance relationship of the Pierce crystal oscillator manufacturer when it is working, and then the definition of the load capacitance is given based on the working principle of the circuit. The crystal oscillator manufacturer shown is in a stable crystal oscillator manufacturer state, and its crystal oscillator manufacturer frequency is fr. According to the nature of the inverter, the phase angle of the inverter output current IS lagging its input voltage VI at this time is 180°

(B) The influence of the amplitude between the corresponding voltage, current and impedance in the AC equivalent circuit of the crystal oscillator manufacturer and the load capacitance on the frequency of the crystal oscillator manufacturer. In practical applications, if the crystal oscillator load capacitance parameters used are not properly selected, Not only the nominal frequency of the crystal oscillator cannot be obtained, but it may also cause unstable operation and even cause the circuit to fail to oscillate normally. The load capacitance is not a parameter of the crystal oscillator itself, but a parameter of the crystal oscillator manufacturer's circuit. Influencing factors of vibration, the Pierce crystal oscillator manufacturer has a simple structure and excellent performance. Its main disadvantage is that the amplifier used must have a sufficiently high gain to compensate for the loss caused by the frequency selection loop.