I have been defining and marketing high performance timing and networking solutions for over 15 years. The new Silicon Labs Si5380 directly addresses a growing challenge in the wireless industry: exploding data demand.
The wireless industry is deploying more wireless coverage using small cells to address high data demand areas. These small cells are growing rapidly with wireless service providers, but they present design challenges because they must be, well, small.
“Small” means less board space, less plastic, and lower cost. Also, because the small cells may be outside on top of a roof or hanging on the side of a building, or in some cases inside in a closet, their performance needs to be immune to changes in operating temperature from heat, cold or power.
Goodbye Cascaded PLL Timing. Hello Si5380, the New Hotness.
Small cell timing and synchronization components today are based on traditional analog-based solutions called cascaded phase lock loops (PLL). The new Si5380 ultra-low phase noise clock generator revolutionizes this older solution on every count.
Cascaded PLL solutions are 1) big, 2) power hungry, and 3) prone to disturbance from noise sources such as power supplies and vibration.
Cascaded PLL Block Diagram
In contrast, the new Si5380 is 1) 66% smaller, 2) 30% lower power, and 3) relatively insensitive to power supply noise and vibration effects. We achieve these impressive numbers using Silicon Labs’ breakthrough architecture, DSPLL.
Why the Si5380 is Better Than Cascaded PLLs
As you might assume, DSPLL uses patented digital techniques to tune an integrated, low power, analog VCO (voltage controlled oscillator).
What you might not assume is that the Si5380’s fourth-generation DSPLL technology provides a fully programmable bank of 12 reference clocks. These clocks are used to provide very precise timing for the analog-to-digital (ADC) and digital-to-analog (DAC) converters used in today's multi-channel, multi-antenna radios required for high bandwidth LTE communications.
Further, its phase noise performance, the spec that really matters in these applications, is better (i.e., lower) and more reliable across temperature, time and noise than any current solution on the market, including the bigger, more power hungry, less flexible, cascaded PLLs.
Taking a closer look at integration, the Si5380 pulls almost all the external components required by cascaded PLLs, including the expensive VCXO and loop filtering components.
Our Application engineers tore down dozens of small cells to measure the space required for cascaded PLL solutions versus our new hotness. The Si5380 reduces board space requirements by an average 187 mm2. That is about the size of the face of a Las Vegas tumbling die.
Board space savings of the Si5380 compared to cascaded PLLs
From a power point of view, the Si5380 saves about 1/3 of the power required by cascaded PLLs. In a small cell form factor, this reduction can make the difference between an over-heated cell or one that doesn’t need a service call for years.
Power savings of the Si5380 compared to cascaded PLLs
Small cells are often mounted in areas with noisy industrial equipment like HVACs and cooling equipment. Any vibration from that equipment can affect the delicate, expensive VCXO (~$2.00 - $4.00 in volume) required by the cascaded PLL.
But not the Si5380. It uses a standard, low-cost crystal (~$0.20-$0.30 in volume) to provide a frequency reference for the Si5380.
In other words, it doesn’t matter if the Si5380 is next to something that is vibrating. The system’s reference clocks will still be rock solid.
Summary and Further Reading
The Si5380’s fourth generation DSPLL has truly reached a pinnacle of simplicity, performance and integration. You can configure its 12 flexible outputs in your labs with simple desktop or iPhone software and immediately benefit from its lower power, smaller size and improved performance. Silicon Labs’ breakthrough innovation and simple setup makes your life easier.
If you would like to read a deeper technical paper on the Si5380, click here.
If you would like to go to the Si5380 page, click here.