SiTime, Silicon MEMS Oscillators and Clock Generators

Packet losses in Ethernet-based networking systems are critical errors that can lead to significant degradation in network performance. In the past, packet loss problems were usually overcome by redesigning the board. Over time, another popular technique for reducing packet losses emerged: Increase the reference clock frequency to Ethernet chipsets.

Ethernet chipsets typically use standard reference frequencies such as:

• 156.25MHz for 10 Gigabit Ethernet
• 125MHz for Gigabit Ethernet, GPON and EPON
• 25MHz for 100 Base-T Ethernet.

In certain network configurations or board designs, packet losses can be eliminated by increasing the reference clock by 25 PPM or 50 PPM (this technique is also known as PLUS PPM CLOCKING). This technique involves using custom frequencies such as 156.25391MHz, 125.00375MHz or 25.000625MHz to drive Ethernet chipsets.

Such customized frequencies are available from quartz crystal suppliers with 12-16 weeks lead time, which does not solve the immediate problem. Customers would rather redesign the board than wait for these custom frequencies to be delivered.

SiTime solves this availability problem with its programmable oscillator platform. SiTime can ship customized samples in as little as 48 hours, and make production quantities available in 2-4 weeks. The flexibility of SiTime's programmable Silicon MEMS oscillators enables system suppliers to employ such error-reducing techniques that enhances system performance without sacrificing oscillator lead time, cost and reliability.
SiTime's SiT8208 and SiT8209 Ultra Performance Oscillators are based on SiTime's high performance programmable platform: and support

• Any frequency between 1 – 220 MHz with 6 decimal places of accuracy
• Any frequency stability from ±10 PPM to ±50 PPM
• -20 ºC to 70 ºC or -40 ºC to 85 ºC operating temperature range
• 1.8V or 2.5-3.3 V operations