Inphi unveils PAM-4 PHY ICs, TIA

Communications semiconductor supplier Inphi Corp. (NYSE: IPHI) has introduced a range of PAM-4 PHY ICs to support high-speed Ethernet applications, including 400 Gigabit Ethernet. The devices include the IN014020-XL (40G), IN015050-SF (50G), IN015025-CA (100G), and IN015025-CD (400G) PHYs, as well as the companion IN2860TA linear transimpedance amplifier (TIA).

The 28-Gbaud TIA is sampling now. The PHYs are production ready and should reach general availability in the fourth quarter of this year, Inphi says.

The PHYs each integrate two channels as well as transmit and receive PAM-4 and forward error correction (FEC) functions on a single IC. They feature the company's programmable InphiNity Core Digital Signal Processing (DSP) Engine and a media-agnostic dual-mode OmniConnect transmitter architecture that makes the chips compatible with both optical and copper interconnects. In the optical domain, the chips will work with VCSELs, EMLs, and DMLs, says Siddharth Sheth, Inphi's vice president, networking interconnect. They also have a special mode for silicon photonics applications, he adds.

The PHY chips also support several programmable FEC options with varying levels of pre-FEC BER performance for applications of 10 km and beyond. They will interface with host ASICs with 10/20/25G NRZ and 56G PAM-4 electrical interfaces while bridging to 20- to 28-Gbaud PAM-4 optics and copper.

Sheth says the devices should find near-term use in a variety of applications. These include the 50-Gbps per-lane single-mode fiber 400 Gigabit Ethernet PMDs recently adopted as baseline specifications (see "Ethernet progresses on several fronts at July IEEE 802.3 plenary meeting"). Other designs that may soon use the chips include single-wavelength 40 Gigabit Ethernet (using 25-Gbps optics) for 2 km and 2x50-Gbps 100 Gigabit Ethernet applications (also with 25-Gbps optics). They also could find use in upcoming offers aimed at 80-km data center interconnect applications as an alternative to coherent transmission approaches.

Sheth added the devices would be compatible with the newly announced Micro QSFP optical transceiver (see "Micro QSFP subject of new optical transceiver MSA").

"With the arrival of 100G QSFP28 optical modules and the availability of 3.2-Tbps switch silicon, we expect 100G 1RU TOR switches to be deployed in cloud data centers starting early next year," commented Loring Wirbel, senior analyst at The Linley Group, via Inphi's press release. "When coupled with Inphi's low-power, highly integrated PAM-4 PHY IC solutions, the market's move to high-density, lower cost 40/100G and next-generation 50/400G systems will become a reality. Inphi's solution is unique not only in the breadth of speeds addressed and provision of companion TIAs, but in its work with driver vendors to assure reference designs for all available physical media."

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