Product Spotlight: The First Integrated Clock for AI Datacenters
Posted By: Jeff Gao


AI has emerged as a mainstream technology, with millions of users almost overnight. This explosive growth has propelled the rapid deployment of AI infrastructure in datacenters and the need for a massive upgrade in high-performance distributed compute and high-bandwidth 400G/800G/1.6TB network equipment.

Precision timing provides the heartbeat for AI infrastructure. It delivers the necessary synchronization across different AI workloads for maximum AI server efficiency. Precision timing is essential for the high-speed networking equipment required to deliver massive amounts of data to the servers used for AI training based on large language models (LLM). To meet the increased demands for higher performance and higher bandwidth brought on by AI, timing technology must innovate at an equally rapid pace.

Chorus Clock Generator by ruler

Chorus clock generator with integrated MEMS resonator in a compact 4 mm x 4 mm QFN package.


SiTime’s latest innovation, the MEMS-based Chorus™ clock-system-on-a-chip (ClkSoC), is the first integrated clock generator for AI datacenter applications. The Chorus ClkSoC integrates a clock IC, a silicon MEMS resonator, and oscillator circuitry into a single chip. By integrating the resonator and eliminating the need for external quartz crystal devices, Chorus simplifies system clock architectures, accelerates design time by up to six weeks and improves reliability and resilience. Chorus clocks are engineered to deliver 10 times better performance in half the size of equivalent quartz-based devices.

Chorus redefines clock technology for AI datacenters and more

The Chorus clock generator family is designed for today’s communications and networking infrastructure equipment. It brings the benefits of MEMS timing technology to AI, datacenter, core/edge/access networking applications and much more. Chorus clocks are equally well suited for other high-reliability applications such as broadcast systems, test instrumentation and power grid infrastructure.

Chorus solves the limitations and design headaches of legacy clock generators. Until now, traditional clock devices typically relied on external quartz resonators or oscillators to provide the input clock reference for phase-locked loops (PLLs). However, using an external quartz timing device on the printed circuit board (PCB) exposes sensitive analog nodes that provide a path for EMI and board noise to couple into the oscillation circuit. Proper PCB design must be ensured to minimize such coupling and keep interference at bay. This requires extra testing and design cycles. Board noise is not the only danger of using quartz devices. Mechanical shock or vibration from fans and other environmental stressors can degrade crystal performance and impact timing stability.

Additionally, with traditional clock generators, designers must select the right load capacitor that matches the crystal’s specific characteristics, which can vary even from the same manufacturer. Load capacitor matching is crucial in ensuring stable, reliable clock operation over temperature. But here's the catch: external crystals and capacitors take up extra board space and can drive up costs, not to mention the headache of managing the supply chain for those capacitors.

Traditional clock generator with external resonator on PCB board

Conventional clocks require external quartz resonators, consuming more board space, increasing design complexity and reducing system reliability and resilience.


Chorus with integrated mems resonator on PCB board

Chorus clock generator with integrated MEMS resonator, reduces board space, simplifies design and increases system reliability and resilience.


Chorus clock generators eliminate the need for quartz crystal devices, along with quartz related performance, reliability, and design issues. Chorus clocks are an integrated timing solutions that combines SiTime’s latest generation of silicon MEMS resonators with low-noise PLLs to deliver exceptional reliability, environmental resilience, and rich features in a single clock-system-on-a-chip (ClkSoC). Along with SiTime’s recently acquired timing products from Aura Semiconductor, Chorus builds on SiTime’s strategy to offer a complete portfolio of highly differentiated timing solutions.

Key elements of the Chorus clock generator architecture include:

  • Integrated MEMS resonator that eliminates issues with external quartz such as capacitive mismatch, activity dips, susceptibility to shock, vibration, and EMI
  • Completely programmable low-noise PLL
  • Four fully programmable clock outputs, each with its own dedicated power supply
  • On chip memory that supports multiple configurations to address in-situ clock tree changes

SiTime’s proven MEMS technology outperforms quartz

By integrating a MEMS resonator, Chorus clock generators provide a better alternative to quartz-based timing technology:

  • 10X higher reliability, eliminating quartz-related performance and reliability issues including field failures
  • 10X better resilience to supply noise, EMI, shock, vibration, and board bending
  • 50% smaller timing footprint on the PCB, by replacing up to four standalone oscillators
Chorus vs traditional clocks with oscillators on PCB boards

A single Chorus clock generator (shown in the center on the right) can drive up to eight single-ended output loads or four differential loads replacing up to four standalone oscillators (as shown on the left).


MEMS integration also accelerates time to market by up to six weeks and simplifies the overall design effort by reducing component count, board real estate, circuit complexity, and exposure to system noise.


SiTime compared to quartz graph showing performance over time

Silicon MEMS timing technology outperforms quartz-based timing in performance and supply chain benefits.


Chorus clock generators are available to customers in two forms, depending on supply chain and design requirements:

  • Blank in-system programmable (ISP) devices provide maximum design flexibility and inventory management.
  • Pre-programmed devices enable system boot-up without software configuration to simplify and accelerate the design and manufacturing process.

Customers can order a fully configured Chorus clock directly from SiTime or choose blank (unconfigured) parts for greater flexibility. SiTime’s state-of-the-art timing configurator tool enables developers to configure blank parts during evaluation or product development. This tool also can be used to reconfigure an already configured Chorus clock generator by burning an entirely new configuration in the device’s on-chip memory.

Chorus Clock Generator rotating

Enabling smarter and faster system design

The Chorus family is a new generation of MEMS-based clock generators that enable smarter, faster, and better system designs by eliminating the design complexities and reducing performance and reliability issues of conventional clock + quartz oscillator solutions.

It’s time to shift to the future of MEMS-based clock technology. Chorus clock generators are currently sampling to strategic customers, with general availability expected in the second half of 2024.

Learn more about Chorus clock generators: 

SiT91211 – 1 to 700 MHz, Low Jitter, ±20 to ±50 ppm MEMS Clock Generator

SiT91213 – 1 to 700 MHz, Ultra Low Jitter, ±20 to ±50 ppm MEMS Clock Generator



May 02, 2024

Apr 25, 2024