What are PECL and LVPECL?
- PECL stands for “Positive Emitter Coupled Logic”. PECL are differential logic outputs commonly used in high-speed clock distribution circuits. PECL requires a +5V supply.
- Low Voltage PECL (LVPECL) denotes PECL circuits designed for use with 3.3V or 2.5V supply, the same supply voltage as for low voltage CMOS devices.
Pros/Cons of PECL Output
Advantages:
- Very good jitter performance due to large voltage swing
- Ideal use in high-speed circuits
- Capable of driving long transmission lines
Drawbacks:
- Larger power consumption due to differential output and external DC biasing compared to single-ended output
- Incompatible with 1.8V supply
Recommended PECL Termination Circuit
Each output is terminated with a 50Ω resistor to a termination voltage of (Vdd – 2V).
What is LVDS Output?
- LVDS stands for Low Voltage Differential Signaling, centered around operating voltage of 1.2V, regardless of power supply.
- LVDS technology is defined by the ANSI/TIA/EIA- 644 industry standard.
- Dynamic Engineers (DEI) has many crystal oscillator product lines with LVDS output options at 3.3V and 2.5V supplies.
Pros/Cons of LVDS Output
Advantages:
- LVDS stands for Low Voltage Differential Signaling, centered around operating voltage of 1.2V, regardless of power supply.
- LVDS technology is defined by the ANSI/TIA/EIA- 644 industry standard.
- Dynamic Engineers (DEI) has many crystal oscillator product lines with LVDS output options at 3.3V and 2.5V supplies.
Drawbacks:
- Reduced jitter performance compared to PECL
Where is LVDS used?
The LVDS standard was created to address applications in the data communications, telecommunications, server, peripheral and computer markets where high-speed data transfer is necessary.
Recommended LVDS Termination Circuit
A single 100Ω termination resistor is needed. Some receiver ICs may include the resistor internally.
Single Level Comparison
2017-3-29
