Fixed Wireless Access (FWA)

5G fixed wireless access (FWA) module and smart antenna mounted on a metal

FWA (fixed wireless access) can provide a faster 5G rollout and improved ROI as it is integrated into existing 4G/LTE infrastructure, to deliver higher bandwidth and faster speed to fiber and other fixed internet lines. SiTime MEMS-based timing solutions are enabling this transition with precision products that offer better stability over temperature, higher reliability, smaller form factors and lower power compared to legacy quartz products.

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SiTime MEMS Timing Benefits

Complete clock tree

Clock system-on-a-chip


Low-jitter differential oscillators

Accurate and robust

Resistant to heat, airflow, vibration

4x better dF/dT (temp slope)

Graceful degradation up to 125°C

Easy to use, built to last

No quartz reliability issues

>1 billion hour MTBF

No cover or shielding needed


5G FWA (fixed wireless access) provides ultra-high bandwidth to deliver heavy content at significantly faster speeds and at a lower cost to fiber and other fixed internet lines. While a seamless shift from traditional networks to 5G front and back haul is difficult to achieve due the large existing investment by the telecom operators in their 4G/LTE infrastructure, some companies are choosing to integrate 5G FWA fronthaul equipment with their 4G/LTE backhaul for a faster rollout and improved ROI.

The preferred mmWaveband being deployed by most carriers is sub-6 GHz or the C-band, specifically 3.3 GHz to 4.2 GHz range as it covers a radius of more than 5 km and supports a maximum throughput of 5 Gbps.

Key reasons for 5G FWA growth are:

  • Reduced connectivity costs: wireless infrastructure is lower cost than fixed wired infrastructure.
  • Faster speeds: 300 Mbps internet access is being touted with the expectation of reaching 1Gbps.
  • Lower latency: 5G offers very low latency making it ideal for environments requiring dependable connectivity.
  • Lower energy use: 5G uses less energy to connect and transmit than alternative options.

Fixed Wireless Access (FWA) Block Diagram

MEMS Timing for Fixed Wireless Access (FWA)

Devices Key Features Key Values
Network Synchronizer
SiT95148  1 to 220 MHz
  • 4 inputs, 11 outputs
  • Up to 2 GHz clock output frequencies
  • 120 fs integrated phase jitter [1]
  • Programmable PLL loop bandwidth, 1 mHz to 4 KHz
  • Digital frequency control
  • -40°C to +85°C
  • 9.0 x 9.0 mm package
  • Multiple clock domains, multiple clock outputs enables complex clock architectures
  • 10x more resistant to vibration and board bending
SiT5501 [2]  1 to 60 MHz
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  • ±10 ppb stability
  • ±0.5 ppb/°C
  • 2x10-11 Allan deviation
  • -40°C to 105°C
  • 7.0 x 5.0 mm package
  • Ensures QoS requirements are met in telecom equipment in hostile environments
Differential Oscillators
SiT9375  25 to 644.5 MHz, 70 fs Integrated Phase Jitter [1]
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SiT9501  25 to 644.5 MHz, 150 fs Integrated Phase Jitter [1]
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  • ±20 ppm to ±50 ppm frequency stability
  • 1.8 V to 3.3 V
  • -40°C to 105°C
  • 2.0 x 1.6 mm, 2.5 x 2.0 mm, 3.2 x 2.5 mm packages
  • Meets demanding jitter requirements
  • Small PCB footprint, easier layout
  • Easy design due to flexibility
  • MEMS reliability
Clock Generator
SiT91211 [3]  1 to 750 MHz, 200 fs Integrated Phase Jitter [1]
SiT91213 [3]  1 to 750 MHz, 90 fs Integrated Phase Jitter [1]
  • 4 differential output clocks
  • ±20 ppm frequency stability
  • 0.01 ps/mV PSRR
  • -40°C to 105°C
  • 4 mm x 4 mm package
  • Simplifies clock tree design with multiple low jitter clocks
  • Programmable clocks add flexibility to complex clocking architectures
  • Better frequency stability and noise immunity in harsh environments
  • Small PCB footprint, compact layout

[1] 12 kHz to 20 MHz integration range; [2]  Contact SiTime for higher frequencies; [3]  Contact SiTime for availability.

SiTime Advantages

SiTime devices offer the following advantages over quartz crystals, which are particularly important for telecom applications:

  • SiT9514x family of synchronizer devices offer a complete synchronization clock tree on a chip. No external crystal is required.
  • dF/dT, in other words the effect of temperature variations on frequency stability, is 4x better than crystal-based TCXOs. This ensures better Quality of Service under airflow, heating, and cooling conditions.
  • Silicon MEMS TCXO offer similar stability as crystal-based OCXO, in a smaller form factor and lower power.
  • SiTime oscillators are factory programmable to any frequency.
  • Silicon MEMS-based timing devices have 30x better reliability than quartz.
  • No activity dip or cold start issues.

MEMS Timing Outperforms Quartz

Better Allan Deviation

Better Vibration Resistance

SiTime – Better Allan Deviation
SiTime – Better Vibration Resistance


Ultra-Low Phase Noise, 156.25 MHz

Smallest Packages

SiTime – Ultra-Low Phase Noise, 156.25 MHz
SiTime – Smallest Packages
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