ORAN Distributed Unit

5G Open RAN brings greater flexibility to networks that are becoming increasingly dense with equipment deployed further from the core, sometimes in less-controlled environments. At the same time, these components need precise synchronization to avoid data packet loss and network interruptions.

This puts a greater demand on the distributed unit (DU) timing solution as it synchronizes the time reference from the core to the fronthaul switch and out to the RU. If the timing reference is lost, the DU must maintain an accurate output clock (holdover) until the connection to the reference is restored. SiTime provides a complete all-silicon MEMS clock tree that is more robust and easy to configure for accurate IEEE 1588 timing.

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SiTime MEMS Timing Benefits

Complete MEMS clock tree

Precision MEMS OCXO

4 input network synchronizer

Integrated MEMS eliminate quartz reliability issues

More robust in real world conditions

±40 ppt/°C dF/dT for accurate IEEE 1588

I²C monitoring for simplified compensation

Immunity to board level noise

Easily configurable clocking

Hitless switching for minimal disruptions

Flexibility of 4 independent time domains

Low wander mode for optimal holdover

ORAN Distributed Unit Block Diagrams

Clock Tree for Open RAN with IEEE 1588

Clock Tree for NPU Based Open RAN DU

MEMS Timing Solutions for Precision Synchronization

Devices	Function	Key Features
OCXO SiT5711 1 to 60 MHz	Stability Engine for IEEE 1588 Clock Recovery	±5 ppb, ±40 ppt/°C dF/dT
Digitally Controlled OCXO SiT5721 1 to 60 MHz	Stability Engine for IEEE 1588 Clock Recovery	±40 ppt/°C dF/dT, I²C Programmable
Network Synchronizer SiT95147 8 kHz to 2.1GHz	Monitor SyncE and eCPRI inputs, facilitate IEEE 1588 loop	120 fs jitter for SyncE, 4 inputs and 8 outputs
Network Synchronizer SiT95148 8 kHz to 2.1GHz	Monitor SyncE and eCPRI inputs, facilitate IEEE 1588 loop	120 fs jitter for SyncE, 4 inputs and 11 outputs