Comms chips

Multilink Shrinks Modulator Module

Multilink Technology Corp.'s (Nasdaq: MLTC) announcement of a new modulator driver yesterday just might help it make a name for itself in this corner of the components market (see MultiLink Launches Modulator).

Multilink's driver product, MTC5529, targets lithium niobate modulators, which are used to gate optical signals that will travel 80 km or further. And it's billed as a significant improvement over other drivers in the marketplace on several fronts, according to the company.

Most notable is the size of the chip, says Gerry Juskovic, Multilink's director of product marketing. "We've taken what was previously implemented in a module -- a great big metal can with metal pins that you solder to the board -- and implemented it in a BGA [ball grid array] package instead." BGAs are a type of integrated circuit package.

For comparison, Multilink's previous generation of modulator drivers came in module packages measuring about 30x25mm across. The new BGA version measures only 16x16mm. Once the space taken by external electrical connections is taken into account, that equates to a 75 percent or better saving in board space, Juskovic says -- something that should be well received by systems vendors, who are continually striving to shrink the footprint of their equipment.

There's another plus point for the BGA package. It can be handled by pick-and-place machines for automated manufacturing, whereas modules have to be manually soldered to the board. That saves systems houses both cost and time when assembling their boards.

Other vendors of modulator drivers, such as Agere Systems (NYSE: AGR) and JDS Uniphase Inc. (Nasdaq: JDSU; Toronto: JDU), all use bulky module-type packaging, Juskovic contends. "We've been asking all our customers if they've seen anything [as small as Multilink's BGA packaged driver] and they say no."

Agere confirmed that it uses a module-type package for its modulator driver. But it also wondered if there might be some functionality missing from the Multilink BGA. "It is not totally equivalent to modules on the market today because those have additional functionality such as bias control loop," says Dan Wilt, product line director for Agere's optical core and metro networks division. The bias control is used to stabilise the DC bias of the lithium niobate modulator, which would otherwise drift over time.

The question now is will other vendors follow suit and start using the smaller, easily assembled BGA package?

Looking further ahead, Agere sees a future where the modulator and driver are integrated in the same package, although the company is not actively working on such a thing right now. "It's on our roadmap, but not this year," says Wilt. It's worth noting, however, that this is a more straightforward vision for a company like Agere, which has competencies in both optics and electronics, than it would be for a company like Multilink, which is a fabless chip maker.

Multilink's MTC5529 costs $700 in quantities of 5000. Samples are available now.

— Pauline Rigby, Senior Editor, Light Reading

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