SiTime’s TCXOs (temperature compensated oscillators) are designed to address synchronizing 5G and 4G+ radios that operate in harsh environments (picture, say, a hot rooftop in Phoenix).

The SiT5356 and SiT5357, Elite Platform member devices were first released in 2017. Nearly two years later, both are now in volume production. 

Elite Platform Super-TCXOs. Image from SiTime

Meeting the Challenges of 5G

5G has been all but inescapable in this industry over the past few years. From updates for developing smart cities at CES to solutions for 5G T&M at DesignCon to regulatory challenges discussed at Mobile World Congress, 2019 has been continually hyped by a market eager for better connectivity.

SiTime is certainly on that bandwagon but appears focused on developing adequate hardware solutions for 5G implementation.

“5G is expected to revolutionize the data economy but first it is re-writing the rules for wireless network deployment,” said Piyush Sevalia, executive vice president of marketing at SiTime.

But, revolutions don’t come without struggle.

One of the toughest issues is that a defining characteristic of 5G is the absolute requirement of reduction in overall system latency. Collision avoidance systems on vehicles and many telemedicine services, as examples, will depend on this characteristic.

This means that there will be a need for far greater time synchronization between the various elements of the complete system. These time and phase requirements are noted under IEEE 1588, a standard around which SiTime developed these devices.

The Elite Platform devices provide high stability and dynamic performance at 105°C for synchronization in 5G/4G+ radios. They deliver timing stability in the presence of environmental stressors caused by real-world issues such as air-flow, temperature changes, vibration, shock, and electromagnetic interference.

Electrical Characteristics

The devices leverage SiTime’s DualMEMS temperature sensing and TurboCompensation technologies for exceptional stability in the presence of environmental stressors. They also integrate multiple on-chip regulators to filter power supply noise, eliminating the need for a dedicated external low dropout (LDO) regulator.

The devices can be factory-programmed to many combinations of frequency, stability, voltage, and pull range. This eliminates the need to customize old-style quartz TCXOs, slashing lead-time and customization costs.

The SiT5356 and the SiT5357 share the following characteristics:

• ±100 ppb stability across entire temperature range of -40°C to +105°C operating temperature
• ±1 ppb/°C typical frequency slope (ΔF/ΔT)
• 3e-11 ADEV (alpha deviation) at 10 second averaging time
• No activity dips or micro jumps
• Resistant to shock, vibration and board bending
• Digital frequency pulling (DCTCXO) via I²C
• Digital control of output frequency and pull range
• Up to ±3200 ppm pull range
• Frequency pull resolution down to 5 ppt
• 2.5V, 2.8V, 3.0V and 3.3V supply voltage

Differentiations between the two family members can be summed up as different frequency coverage and output.

The SiT5356

• Factory programmable to any frequency from 1 MHz to 60 MHz in 1 Hz steps
• LVCMOS or clipped sinewave output

The SiT5357

• Factory programmable to any frequency from 60-189 MHz and 200-220 MHz in 1 Hz steps
• LVCMOS output

Block diagram and pinout for members of the Elite Platform member devices. Image from SiTime

Regulatory and Environmental Characteristics

• RoHS- and REACH-compliant
• Lead-free, halogen-free, antimony-free

The devices are available in a 5.0 by 3.2 mm² SOIC-8 package.

Around the Industry

The advent of 5G is one of the focal points of today’s electronics industry. Not surprisingly, there are many manufacturers making products broadly similar to SiTimes’ two devices. However, crystal-controlled oscillation is generally what has, so far, been the market's choice.

SiTime may have this particular MEMS application to itself for now, but given the popularity and applicability of MEMS and explosion in 5G networks, it is doubtful that the exclusivity will last for long.

It is worth noting that Intel and SiTime have collaborated in building 5G applications with MEMS technology. The fact that 5G powerhouse Broadcom is now the world’s top MEMS vendor is also noteworthy.

For more information, Please feel free to contact us. zora@semilotec.com