MultiPhy raises $17M to develop 100G serial interfaces

Start-up MultiPhy has raised U.S. $17 million to develop 100-gigabit single-wavelength technology for the data centre. Semtech has announced it is one of the companies backing the Israeli fabless start-up, the rest coming from venture capitalists and at least one other company.

MultiPhy is developing chips to support serial 100-gigabit-per-second transmission using 25-gigabit optical components. The design will enable short reach links within the data centre and up to 80km point-to-point links for data centre interconnect. 

Source: MultiPhy

“It is not the same chip [for the two applications] but the same technology core,” says Avi Shabtai, the CEO of MultiPhy. The funding will be used to bring products to market as well as expand the company’s marketing arm.

There is a huge benefit in moving to a single-wavelength technology; you throw out pretty much three-quarters of the optics

100 gigabit serial

The IEEE has specified 100-gigabit lanes as part of its ongoing 400 Gigabit Ethernet standardisation work. “It is the first time the IEEE has accepted 100 gigabit on a single wavelength as a baseline for a standard,” says Shabtai.  

The IEEE work has defined 4-by-100 gigabit with a reach of 500 meters using four-level pulse-amplitude modulation (PAM-4) that encodes 2 bits-per-symbol. This means that optics and electronics operating at 50 gigabit can be used. However, MultiPhy has developed digital signal processing technology that allows the optics to be overdriven such that 25-gigabit optics can be used to deliver the 50 gigabaud required. 

“There is a huge benefit in moving to a single-wavelength technology,” says Shabtai. ”You throw out pretty much three-quarters of the optics.”

The chip MultiPhy is developing, dubbed FlexPhy, supports the CAUI-4 (4-by-28 gigabit) interface, a 4:1 multiplexer and 1:4 demultiplexer, PAM-4 operating at 56 gigabaud and the digital signal processing. 

The optics - a single transmitter optical sub-assembly (TOSA) and a single receiver optical sub-assembly (ROSA) - and the FlexPhy chip will fit within a QSFP28 module. “Taking into account that you have one chip, one laser and one photo-diode, these are pretty much the components you already have in an SFP module,” says Shabtai. “Moving from a QSFP form factor to an SFP is not that far.”

MultiPhy says new-generation switches will support 128 SFP28 ports, each at 100 gigabit, equating to 12.8 terabits of switching capacity.

Using digital signal processing also benefits silicon photonics. “Integration is much denser using CMOS devices with silicon photonics,” says Shabtai. DSP also improves the performance of silicon photonics-based designs such as the issues of linearity and sensitivity. “A lot of these things can be solved using signal processing,” he says.

FlexPhy will be available for customers this year but MultiPhy would not say whether it already has working samples.

MultiPhy raised $7.2 million venture capital funding in 2010.