Top of Rack Switch / Leaf Switch

Top of Rack Switch / Leaf Switch

IEEE 1588 is becoming the de facto standard for better performance in data centers. As Synchronous Ethernet (SyncE) replaces Ethernet, use of a TCXO or OCXO reference clock in top-of-rack and leaf switch is needed. SiTime offers a complete MEMS-based clock tree solution that performs better in real-world operating conditions.

Elite Platform® Super-TCXOs® and Emerald OCXOs provide essential stability and reduce time error through better frequency over temperature slope. Cascade™ network synchronizers / jitter cleaners / clock generators, used to filter jitter in recovered clocks, have an integrated resonator that simplifies development and reduces field failures. When SyncE and IEEE 1588 are not needed, SiTime differential oscillators offer sub-100-femtosecond jitter and low power. Together they offer a complete and robust clock tree.

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SiTime MEMS Timing Benefits

Complete MEMS clock tree

Integrated MEMS

Stratum 3E MEMS OCXO


More robust in real world conditions

4x better dF/dT for best time sync

70 fs rms jitter, excellent PSNR

Resistant to airflow, heat, vibration

Integrated MEMS, easy to use

No external quartz

No quartz reliability issues

No cover or shielding needed

MEMS Timing Solutions with SyncE and IEEE 1588

Image: Microwave block diagramSiT57xxSiT53xx,

MEMS Timing Solutions without SyncE and IEEE 1588

Microwave block

MEMS XO + Buffer Alternative Timing Solution

Microwave block

MEMS Timing Solutions

Devices Function Frequency Key Features
SiT535x Super-TCXOs Reference clock for jitter cleaner and IEEE1588 1 to 220 MHz ±100 ppb, ±1 ppb/°C 105°C
SiT57xx OCXOs 1 to 60 MHz ±5 ppb, ±0.04 ppb/°C
SiT9514x Clock Generator Ethernet 8 kHz to 2.1GHz 4-in, 11-out, 4-PLL
SiT9514x Network synchronizer, Jitter cleaner Ethernet, processor 8 kHz to 2.1GHz 4-in, 11-out, 4-PLL

SiT9501 Differential XO

SiT9375 Differential XO

Ethernet, FPGA 1 to 725 MHz 0.07 to 0.25 ps jitter, 105°

Data Center Architecture

A leaf switch (or top-of-rack ToR switch) aggregates server traffic between the spine switches and either the core network or servers in the data-center campus. As bandwidth increases in next-gen deployments, higher performance is specified by IEEE 1588, placing a greater demand for high-performance timing solutions that withstand airflow, heat, and vibration. 

Image: TOR Leaf Switch data center diagram

MEMS Timing Outperforms Quartz

Better Stability

Better Frequency Slope

Image: Emerald OCXO Outperforms Quartz in Stability


Image: Emerald OCXO Outperforms Quartz in Frequency Slope


Better Vibration Resistance

Better Allan Deviation

Image: Emerald OCXO Outperforms Quartz in Vibration Resistance


Image: Emerald OCXO Outperforms Quartz in Allan Deviation


Excellent Phase Noise, 156.25 MHz

Better PSNR (Power Supply Noise Rejection)

Image: Emerald OCXO Outperforms Quartz in Phase Noise


Image: Emerald OCXO Outperforms Quartz in Power Supply Noise Rejection


Watch Video: SiTime Elite Super-TCXO Dynamic Performance vs. Quartz TCXO

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