SiGe power problems may send IC makers back to CMOS, says AMCC executive

SANTA CLARA, Calif. -- While silicon-germanium (SiGe) technologies promise to deliver the next wave of high-speed communications chips, some unexpected power issues with this process could force IC suppliers back to traditional CMOS, said an executive from Applied Micro Circuits Corp. (AMCC).

Some communications-oriented devices, based on SiGe, consume too much power, especially in next-generation 40-gigabits-per-second (OC-768) networking applications, declared Greg Winner, senior vice president of engineering and quality at San Diego-based AMCC.

"We have 5-volt SiGe-enabled devices today, going to 3.3-volt," Winner said. "But SiGe has some power issues in that we can't get the technology down to 1.8-volts in OC-768 applications," he said during a presentation at the DesignCon 2002 conference here on Wednesday.

For OC-768, system manufacturers will continue to use select devices, based on SiGe, gallium-arsenide (GaAs) and other non-CMOS process technologies, he pointed out in an interview with SBN after the presentation.

But the power issues are forcing AMCC and other chip makers in the networking sector to develop some of the more critical parts, based on traditional CMOS technologies, Winner said. In fact, AMCC is working with silicon foundry giant United Microelectronics Corp. (UMC) in Taiwan to develop devices for OC-768 applications, based on next-generation 0.10-micron, CMOS-based processes, he said.

Ironically, AMCC itself is developing and selling a line of high-speed chips, based on SiGe technology from IBM Corp.'s Microelectronics Division. IBM also makes SiGe-based devices on a foundry basis for the San Diego-based company.

Winner did not mention IBM or other SiGe-based technology developers by name during the presentation, but he noted that AMCC and its customers require lower-power SiGe devices.

During the presentation, Winner made his point by explaining the limitations of today's OC-768 module products, based on SiGe-enabled components. In general, the module for networking equipment consists of several key devices, such as a limiting amplifier, transimpedance amplifier, and send/receive devices.

One of the biggest problems with today's modules is that the separate SiGe-enabled transmit and receive devices consume too much power, he said. At present, the company's devices run at 15 watts, he said. "The challenge is to lower the transmit and receive chain down to 3 watts," he said during the presentation.

Even the newfangled, SiGe-based processes will not lower the power consumptions to this requirement, he claimed. The AMCC executive was reportedly referring to the new 200-GHz, SiGe-based technologies fromConexant, IBM, and other providers.

AMCC is not throwing in the towel on SiGe. On the contrary, the company will continue to use SiGe for the amplifier and other portions of the module, he said.

But to reduce the power consumption, the AMCC executive said the company is looking at traditional CMOS processes to develop the high-speed send and receive devices, he said.

The company is not banking on existing 0.13-micron, CMOS technologies to lower the power for these devices. But rather the company is waiting for next-generation 0.10-micron processes, he said.

AMCC is working with UMC to develop these devices. The Hsinchu-based company is also making several other CMOS-based devices on a foundry basis for AMCC.

"We are working very closely with UMC," Winner said, noting that UMC's 0.10-micron, CMOS-based technology will be shipping in volumes in 2003.