1 to 700 MHz, Ultra Low Jitter (70 fs), ±20 to ±50 ppm MEMS Clock Generator


The Chorus™ SiT91213 clock generator is designed for low-power, low-jitter applications. It has ultra low jitter at 70 fs (typ). This device has a single clock domain and can drive up to eight low-skew single-ended output loads or four low-skew differential loads.

The SiT91211 integrates an internal MEMS resonator as the frequency source for the internal PLL. By integrating a MEMS resonator, the dependency on quartz crystals is eliminated along with quartz related performance, reliability, and design issues like activity dips and matching requirements.

This highly flexible clock has fully configurable output frequency, clock output buffer type (differential and LVCMOS) and individual output enables, through the serial interface. Internal monitor flags and alarm conditions can be configured to be reported through GPIOs. In addition, the SiT91211 has configurable spread-spectrum clocking.

The device is compliant with PCIe Generation 1-6.

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4x4 mm, 24-pin QFN Clock Generator package
"Specs" "Value"
Frequency Stability (ppm) ±20 ppm (-40°C to 105°C), ±50 ppm (-40°C to 105°C)
Operating Temperature Range (°C) -40 to 85, -40 to 105
Package Type (mm²) 4x4 mm, 24-pin QFN
Number of Outputs 8 single-ended, 4 differential
Output Frequency Range 1 to 700 MHz (differential), 1 to 220 MHz (LVCMOS)
Number of PLL/Clock Domains 1 PLL
Phase Jitter (rms) 70 fs (typ.)
PCIe Support Gen 1 to Gen 6
Voltage Supply (V) 1.8, 2.5, 3.3
Availability Sampling
  • Standard Frequencies from 1 MHz to 700 MHz
  • Fully integrated MEMS-based clock source
  • Configurable clock domain and 4 differential outputs or 8 single-ended outputs
  • Configurable output clock drivers:
  • Excellent frequency stability:
    • ±20 ppm (-40°C to 105°C)
    • ±50 ppm (-40°C to 105°C)
  • Configurable spread-spectrum clock generation
  • Compliant with PCIe Generation 1 to 6
  • Clock fault monitors (Lock Loss)
  • Supply voltage of 1.8 V to 3.3 V
  • Low phase jitter, 100 fs maximum (12 kHz-20 MHz)
  • Resistant to shock/vibration
  • Max. Operating range: -40°C to 105°C
  • I2C or SPI serial interface for configuration
  • QFN 24 pin 4 x 4 mm, 0.5 mm pitch (wettable flank) package
SiT91213 Functional Overview
  • Data Centers
  • SmartNICs
  • AI/ML Compute Offload / Accelerators
  • Datacenter Switches & Routers
  • Over-the-top (OTT) Streaming Devices
  • Rack Server
  • High-speed Serial Link
  • PCIe
  • SerDes
  • Host Bus Adapters (HBA)
  • Optical Communications
  • Optical Transport Network (OTN) Clocking for Framers, Mappers & Processors
  • Cable Model Termination System (CMTS)
  • 5G Infrastructure
  • 4G / 5G RRH, DU
  • Test & Measurement
  • Instrumentation
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