<FONT COLOR="RED"><B>Electronica:</B></FONT> Philips says BiCMOS process sports SiGe, GaAs speeds

Electronica: Philips says BiCMOS process sports SiGe, GaAs speeds
MUNICH, Germany — At this year's Electronica exhibition, Philips Semiconductors will announce the production release of a BiCMOS process that it says offers the fastest bipolar transistors available. The benefit for designers will be a process that can deliver gallium arsenide and silicon germanium speeds at two-thirds the cost of those more exotic processes, Philips said.

Though Qubic3 has a 0.5-micron minimum feature size — relatively conservative, compared with mainstream CMOS — Philips claims the process will provide the best platform for digital and RF integration in mobile communications. In many parameters, Qubic3 is close to IBM's BiCMOS SiGe process, which uses the same design rules.

Development of the first chips to use Qubic3 is already well under way. About 25 circuits are said to be in design, with rollout expected to start in January and to continue through 1999.

"What we have here is the technology to integrate the baseband and the RF" in mobile communications, said Neil Morris, senior manager for advanced technology development at Philips Semiconductors (Albuquerque, N.M.). That suggests Philips believes the process could support single-chip mobile phones.

"What we've done is made a technology platform for the engineer. Technologically we can deliver a single-chip solution, and we are looking at this," Morris said. "Will [such a solution become] a product? That depends on customers' specifications."

Theo Claasen, Philips Semiconductors' chief technology officer, said the company has "pushed the performance of silicon to new standards for speed but not at the expense of power consumption or a premium price." Claasen said Qubic3 chips will enable new classes of high-performance mobile-communications devices, such as wrist phones that would let users check data on the Internet, place video telephone calls and transmit software, video clips and data.

The bipolar portion of the Qubic3 process has a maximum frequency of around 70 GHz — double the bipolar-industry norm of 30 to 40 GHz, and comparable with SiGe or GaAs, according to Philips. The transition frequency, at which gain drops below 1, is at around 30 to 34 GHz depending on the measurement conditions; that's said to be higher than for other bipolar processes. "Qubic3 can give a superior-performance LNA [low-noise amplifier] even to our own, internal GaAs," said Morris.

Leading bipolar silicon processes from many companies are already capable of operating at the 1.8 GHz to 1.9 GHz of digital cellular communications and even at the 1.9 GHz to 2.2 GHz of the third-generation mobile communications systems due to be deployed after 2000. But Morris asserted that "Qubic3 gives us more headroom. As you push a technology to its maximum, you compromise on power and noise."

He said he expects Qubic3 to address applications up to around 5 GHz. Work has already begun at Philips on Qubic4, which will move to 0.25-micron geometries and deliver an fmax of around 90 GHz, and on Qubic5, which may see Philips' first commercial use of silicon-germanium.

"We've been doing research on silicon germanium for 10 years now and on gallium arsenide for much longer. We're aware of their capabilities, but we've decided to take the silicon-only approach," Morris said.

The cost differential of 30 percent that Philips claims for using silicon compared with SiGe is in line with that stated by proponents of SiGe technology, although they have emphasized taking SiGe to performance levels that bipolar silicon could not previously achieve.

Morris put the cost differential in the context of the number of masks required to produce an IC. "Our mask count is 26 to produce a circuit with four layers of metal. The number is 30 to 32 typically for silicon germanium with only three layers of metal."

He emphasized that Qubic3 has been developed in conjunction with Philips' circuit designers and optimized not purely for speed but also to reduce power consumption and noise in the mobile-communications applications that are likely to drive the next stage of industry growth.

Morris said that a low-noise amplifier for mobile communications could be constructed with a noise figure of 0.6dB. The Qubic3 process also includes the ability to build four different types of resistors, high-quality capacitors and inductors on-chip.

"The strategic importance of such technologies in the marketplace is so strong, especially for creating ultra-fast RF front-end ICs for the mobile-phone market, that we can already see a significant demand for this new generation of Qubic technology," said Claasen.

The first product to use the Qubic3 process will be a 3.5-GHz synthesizer.