The difference between differential crystal oscillator and passive crystal oscillator

＞ Working principle
· Differential crystal oscillator (functional crystal oscillator)
Differential crystal oscillator eliminates common mode noise and realizes a higher performance system by using two signals with completely opposite phases. Differential output waveforms include LVDS, LVPECL, HCSL, etc. Differential is an active crystal oscillator with an internal integrated oscillation circuit. It can directly output a stable clock signal with external power supply.

· Passive crystal oscillator (crystal resonator)
It is essentially a passive component that relies on external circuits (such as the oscillator inside the MCU) to start oscillation. It needs to match the load capacitor and resistor to work stably.

①The differential crystal oscillator generally has 6 PIN pins, and the test circuit is as follows:

②Passive crystal oscillator
Two-pin or four-pin package (no power pin), external load capacitor and matching resistor are required.

＞ Performance characteristics

＞ Application scenarios
· Differential crystal oscillator:
High-speed communication (such as FPGA, SerDes, etc.).
Systems sensitive to EMI (such as RF, aerospace, etc.).
Scenarios where clock signals need to be transmitted over long distances.

· Passive crystal oscillator:
Low-cost embedded systems (such as STM32, 51 microcontrollers).
Consumer electronic products (such as home appliances, toys).
Scenarios with relatively low requirements for clock accuracy.

＞ Summary of key differences
Signal type: differential output vs single-ended output.
Integration: Differential crystal oscillator has built-in oscillator, passive crystal oscillator requires external circuit drive.
Anti-interference: Differential signals are more suitable for high-speed and high-noise environments.
Design complexity: Passive crystal oscillators need to match capacitors/resistors, while differential crystal oscillators are plug-and-play.