Why passive crystal oscillator is passive components?
The passive components crystal oscillator cannot start to oscillate by itself, and can work normally only when the oscillation circuit meets its working requirements.
Therefore we often call it passive components.
Passive components: refers to the circuit components that do not affect the basic characteristics of the signal,
and only allow the signal to pass but have not been modified. Common passive components：
resistors, capacitors, inductors, ceramic oscillators, crystal oscillators, transformers, surface acoustic filters, passive sensors, etc.
Active components ：refers to the circuit device that contains the amplification control element
(such as semiconductor transistor, MOS tube, etc.) in the circuit. Commonly used devices:
CPU, operational amplifier, memory, FPGA, CPLD, etc. Active components are the core of electronic circuits.
All oscillation, amplification, modulation, demodulation, and current conversion are inseparable from active components.
PS：Passive components crystal oscillators are divided into passive crystal oscillators and active crystal oscillators. The above refers specifically to passive crystal oscillator series.
SMD crystal oscillator datasheet