Structure of the Quartz Crystal
(无源晶振结构)
Simply put, an oscillator is a device that can convert DC power into AC power without external signal excitation. The so-called “oscillation” implies alternating current.
简单地说，晶体振荡器是一种无需外界信号激励，就能将直流电源转换成交流电源的器件。所谓“振荡”是指交流电。
Oscillator Circuit
( 无源晶振振荡电路)
- Parallel Type Quartz Crystal Oscillator
(并联式石英晶体振荡器)
Frequency Characteristics of Parallel Quartz Crystal Oscillator
Quartz crystal works between fs and fp, which is quite a large inductance, and forms a capacitive three-point oscillator with C1 and C2. Because the Q value of the quartz crystal is very high, which can reach more than several thousand, the circuit can obtain high oscillation frequency stability.
石英晶体工作在 fs 和 fp 之间，呈现相当大的电感量，与 C1 和 C2 构成电容式三点振荡器。由于石英晶体的 Q 值很高，可以达到几千以上，所以电路可以获得很高的振荡频率稳定度。
(并联石英晶体振荡器的频率特性)
- Series type quartz crystal oscillator
(串联式石英晶体振荡器)
Frequency Characteristics of Series Quartz Crystal Oscillator
The quartz crystal works at fs, which is resistive and has the smallest impedance, the strongest positive feedback, and zero phase shift, which meets the phase balance condition of oscillation.For frequencies other than fs, the impedance of the quartz crystal increases, and the phase shift is not zero, then the oscillation condition is not met, and the circuit does not oscillate.
石英晶体工作在 fs ，是电阻性的，阻抗最小，正反馈最强，相移为零，满足振荡的相位平衡条件。对于 fs 以外的频率，石英晶体阻抗增大，相移不为零，则不满足振荡条件，电路不振荡。
(串联石英晶体振荡器的频率特性)
Oscillator Circuit Start-up Process
(振荡电路起振示意图)
When the oscillating circuit is powered on, the current of the transistor increases abruptly from zero, and the sudden change current contains a wide spectrum component.
振荡电路通电后，晶体的电流从零突然增大，且突变电流中含有宽谱成分。
The start-up process of the circuit is very short! As long as the circuit satisfies the starting conditions, after the oscillator is powered on, there will be an output signal with stable amplitude at the output.
电路的启动过程很短！只要电路满足启动条件，晶体振荡器通电后，在输出端就会有一个振幅稳定的输出信号。
