PAM-4 and the Path to 100G and 400G in the Data Center

Feb. 14, 2017

PAM4 Blog.jpg (network server room)Much has been written about the proliferation of data center infrastructure in recent months, with new data center build outs announced at a rapid clip, each with facility footprints so large that they’re commonly measured in football fields. This aggressive build out activity will augment existing data center infrastructure that’s already massive in scale.

For data center infrastructure both new and old, system designers are moving quickly to implement 100G interconnects to better accommodate the deluge of east-west data center traffic driven by burgeoning user demand for online data and multimedia. Experts forecast that the 100G market is expected to exceed 15 million ports by 2020, and the ground is already being laid for the subsequent transition to 400G.


The need for 100G connectivity in the data center has been crystal clear, but the pathway to mainstream 100G adoption was somewhat less so. Early implementations of 100G optical transceivers utilized the NRZ signal modulation scheme, which proved to be a viable solution. But as is the case with any major technology transition, system designers sought a clear industry standard that resolved any lingering ambiguities among competing approaches – an agreed-upon standard that they could coalesce around with confidence.

The single-wavelength (lambda) PAM-4 modulation scheme has emerged as that standard. Advocated by AppliedMicro, Cisco and others, and adopted by the IEEE, PAM-4 has proved to be the most cost-effective, efficient enabler of 100G and 400G in the data center to date. For 100G transceivers, single-wavelength PAM-4 technology reduces the number of lasers to one and eliminates the need for optical multiplexing. For 400G implementations, only four optical assemblies are needed, representing a major opportunity for data center operators to reduce their CAPEX and OPEX with an extremely compact and energy efficient module.


MACOM joined forces with AppliedMicro and BrPhotonics to demonstrate the first ever successful demonstration of 100G single wavelength PAM-4 technology at ECOC 2016. The demo blended AppliedMicro’s 16nm FinFET 100Gb/s PAM4 DSP, a BrPhotonics TFPS modulator, and a MACOM TIA. It was an eye-opening demonstration that prompted one industry expert to conclude that, “this technology is coming faster than many people think.”

That was a prescient observation. In a similarly forward-looking move, MACOM cemented our collaboration with AppliedMicro when we acquired it earlier this year, combining our core strengths in optical networking technology to help accelerate the volume deployment of 100G transceivers for data center applications, with a clear pathway to 400G. Working side by side, our combined team of technology experts are collaborating with customers to help lower optical infrastructure costs and boost overall port density in the data center, whether they’re implementing legacy NRZ or next-generation PAM-4 gear.

MACOM’s acquisition of Applied Micro brings together two complementary portfolios, enabling us to offer a proven solution including a PAM-4 DSP, linear driver and linear TIA specifically designed to enable 100G per lambda modules. For more information about our product portfolio and technology strategy, be sure to visit us at OFC 2017 (Booth #1736).


All financial guidance projections referenced in this post were made as of the publication date or another historical date noted herein, and any references to such projections herein are not intended to reaffirm them as of any later date. MACOM undertakes no obligation to update any forward-looking statement or projection at any future date. This post may include information and projections derived from third-party sources concerning addressable market size and growth rates and similar general economic or industry data. MACOM has not independently verified any information and projections from third party sources incorporated herein. This post may also contain market statistics and industry data that are subject to uncertainty and are not necessarily reflective of market conditions. Although MACOM believes that these statistics and data are reasonable, they have been derived from third party sources and have not been independently verified by MACOM.