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Silicon Labs Si540 & Si545 Ultra Series Crystal Oscillators

Silicon Labs Si540 and Si545 Ultra Series crystal oscillators are ultra-low jitter, low phase noise crystal oscillators for any frequency from 200 kHz to 1500 MHz. This helps to reduce design risk in high-speed applications tighter timing margins, such as in optical transport and ethernet, broadcast video, data center, and test and measurement applications.

Minimizing jitter is increasingly critical in high data rate communications applications, such as 16G fiber channel, 100G Ethernet, and 400G OTN among others. Excessive jitter leads to high bit-error rates, lost traffic, or complete loss of communication, but “high” jitter can be as low as 130 fs.

The Si540 and Si545 address this challenge using the all-digital architecture of Silicon Lab’s 4th generation DSPLL, which uses a simple, high-quality, fixed frequency crystal to generate any frequency and can easily be customized to individual design needs. The oscillators offer a digitally-controlled oscillator with a step size less than 1 ppb to eliminate phase delay. Innovative phase error cancellation removes PLL noise, while on-chip LDOs provide high PSRR, allowing the oscillators to be used with switched-mode power supplies. The oscillators are also extremely stable, with temperature stability rated at 20 ppm, and total stability at 50 ppm. This ensures consistent performance across process, voltage, and temperature variations.

This approach allows the Si540 and Si545 to produce standard or custom frequencies from 200 kHz to 1.5 GHz, while maintaining jitter as low as 80 fs for the Si545 or 125 fs for the Si540 across the entire operating range.

For design flexibility, 1.8 V, 2.5 V, and 3.3 V supplies are supported from one part number, and output formats include LVPECL, LVDS, CML, HCSL, CMOS, and Dual CMOS. The oscillators are factory programmed to the desired frequency, output format, and output enable pin location and polarity, which also provides for 100% electrical testing of every device. Dual, quad, and I2C variants are available for both the 80 fs and 125 fs ratings, and the oscillators are packaged in 3.2 mm x 5 mm or 5 mm x 7 mm ceramic leadless chip carriers.  

To support designers and simplify development, Silicon Labs offers its Oscillators Phase Noise Lookup Tool, an online tool with 1000s of searchable phase noise plots based on part number, output format, and output frequency. For more information on Silicon Labs’ Si540 and Si545 Ultra Series Crystal Oscillators and the benefits of ultra-low jitter oscillators, visit


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