Quad-channel, 28 Gbaud linear driver for PAM-4 comms links
The MAOM-003419 is a low power electroabsorptive modulated laser (EML) driver with high gain, high bandwidth, and output voltage capability up to 2 Vpp while it consumes less than 500 mW of power. The device has differential inputs to provide common-mode rejection and single-ended output to drive industry standard EMLs. The MAOM-003419 is available in a small form factor surface mount package while also integrating the high frequency bias T for the EA modulator.
MACOM says that the company, “has achieved excellent performance with our PAM-4 chipset IP, and we believe this product is a great addition to enabling the next generation of 200G and 400G optical connectivity for enterprise and datacentre applications.”
The device takes its place as part of a series of trends that MACOM identifies as datacentres and metro networks scale up through 100, 200 and 400G rates. The company has strengthened it position in optical and photonic products in recent years, through a series of acquisitions and organic growth; it now sees itself, for example, as the foremost supplier in modulator drivers for long-haul and metro networks. Over 50% of the company’s revenues now come from its photonics product lines.
One such trend is higher levels of integration; in the case of the MAOM-003419, four modulators that were previously individual packages are combined in one; that device is a gallium arsenide device that operates in conjunction with a clock and data recovery chip, which is a silicon-germanium (SiGe) IC. For this pairing, the next step is to integrate both parts on a single multi-chip substrate. MACOM envisages other comparable integration steps with circuit blocks, such as TIA (transimpedance amplifier) and laser functions.
MACOM has developed a technology it calls self-aligned etched facet technology, or SAEFT, for volume manufacture of L-PICs or laser-photonics-ICs. The company’s etched-facet laser dice are a step forward from prior cleaved-facet laser techniques, requiring fewer manufacturing processing steps and allowing test at wafer level (before individual devices are separated. However, the process technology that fabricates them remains incompatible with that for the photonics ICs to which they must closely couple, so a 2-chip solution is always required. In SAEFT, rather than individually assembling and aligning the paired devices, the laser is fabricated to be a precise physical ‘fit’ in an etched cavity in the PIC.
The laser element is ‘flipped’ and ‘dropped in’ to the PIC. Not only is alignment, as the mnemonic suggests, automatic, but a further step to volume production is available. In development and early production, assembly of the flip-chip configuration is carried out individually; MACOM plans to move that step to assembly at wafer scale (wafer-to-wafer) before dicing individual L-PICs. The company expects to see the cost benefits of the shift from, in effect, a serial assembly process to a parallel one.
MACOM; www.macom.com
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