High-Speed 25Gbps 1:2 CML Fanout Buffer with Internal Termination: The Microchip SY89544UMG-TR

In the relentless pursuit of higher data rates within data centers, telecommunications infrastructure, and high-performance computing, the integrity of clock and data signals is paramount. As speeds push into the multi-gigabit regime, even minor signal degradation can lead to catastrophic system errors. Addressing this critical need for signal distribution, Microchip's SY89544UMG-TR emerges as a high-performance solution designed to faithfully replicate and fan out very high-speed signals with minimal added jitter and distortion.

This device is a 1:2 fanout buffer utilizing Current Mode Logic (CML) technology, which is the preferred architecture for achieving the highest data rates with low noise. Its primary function is to take a single differential CML input signal and generate two identical, buffered differential CML output copies. This capability is essential for applications where a single high-quality source—such as an oscillator or a serializer output—must drive two separate downstream components, like two FPGAs, two ASICs, or two optical modules, without compromising signal quality.

The standout feature of the SY89544UMG-TR is its exceptional 25 Gbps operational bandwidth. This speed positions it perfectly for next-generation applications, including 25G and 100G Ethernet (using 4x25G lanes), 5G fronthaul/backhaul, InfiniBand, and proprietary high-speed interconnects. Beyond mere data rate, the device is engineered for superior signal integrity, characterized by very low additive jitter and tight channel-to-channel skew, ensuring the synchronized arrival of clock or data pulses at their destinations.

A significant design advantage is its internal 50Ω termination resistors. By integrating these termination resistors on-chip at both the inputs and outputs, the SY89544UMG-TR simplifies board layout, reduces the bill of materials (BOM), and minimizes the parasitic elements that external discrete resistors would introduce. This integration is crucial for maintaining signal fidelity at 25 Gbps, where any impedance mismatch can cause detrimental reflections.

Housed in a compact, 16-pin QFN (3mm x 3mm) package, the device offers a small footprint valuable in space-constrained designs. It operates over a wide industrial temperature range and supports a single -3.3V power supply, contributing to its versatility across different operating environments.

ICGOOODFIND: The Microchip SY89544UMG-TR is a critical enabler for high-speed digital systems, providing a robust and simplified solution for distributing 25Gbps signals. Its integration of internal termination, low power consumption, and outstanding jitter performance makes it an excellent choice for designers aiming to push the boundaries of speed and reliability while simplifying their PCB design.

Keywords: 25Gbps, CML Fanout Buffer, Internal Termination, Signal Integrity, Additive Jitter