Why do we need “differential output” oscillators?

In recent years, it has become common to use differential transmission for the purpose of high-speed transmission.

In terms of hardware (HW) design around the clock, single-ended clocks are still used up to around 100MHz, but above that, the differential interface is used more and more.

The image of the signal difference with the single end is below.

While proceeding with the selection of key devices such as FPGAs and network switches,

Various issues arise, such as the need for noise countermeasures, the difficulty of routing signals, and the need for a differential clock source (reference clock) on the key device side of the load.

Therefore, a “differential output oscillator” is effective as a clock source.

The main advantages are "high speed and excellent stability" and "noise resistance".

To avoid design failures - What SiTime's differential output oscillators can do -

On the other hand, in order not to fail in the design, "correct termination setting" and "selection of high-quality clock with no waveform skew" are important points.

In order to overcome these issues and take advantage of the excellent merits, please try the "differential output oscillator using MEMS".

・Recommended point 1: Support for a wide range of interfaces

→ LVPECL,LVDS,HCSL,Widely compatible with Low-power HCSL. If you have any other requests, please feel free to contact us.

SiTime's original function called Flex-Swing is also installed in some of the latest products.

This is an output similar to LVPECL, but with configurable VOH/VOL and amplitude.

It can be configured flexibly according to the unusual requirements of the receiving side.

・ Recommended point 2 "Performance"

→ For differential output products, 2016 size, the smallest size in the industry, is adopted. There is also an advantage in the demand for miniaturization of the system.

Incredibly low jitter Achieves 70 fs (Phase Jitter RMS). Conventional wisdom about programmable oscillators does not apply to SiTime.No!

In addition, it supports a wide frequency range (1MHz to 750MHz).

・ Recommended point 3 "Technical support for correct termination design"

→ There are plenty of related manuals, so you don't have to worry about designing.

Below are the recommended terminations for the popular "SiT912x" series as differential output oscillators for each interface.

Please feel free to contact Macnica regarding any other products or questions.

        About the output termination of SiT912x (Source: SiTime homepage)

At the end

What did you think.

This time, I briefly explained the merits of differential output oscillators and points for selection.

Please feel free to contact us if you have any questions during the design process.

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