A Perspective On BiCMOS Trends

Abstract

The era of modern BiCMOS technology started in the early 1980s [10.1,10.2] with the promise of significantly improving SRAM and logic (gate array) performance and greater integration of mixed-signal analog systems. Over a decade latter what has been realized? The fastest commercially available SRAMs in the world, ranging in densities from 1K to 1M, are BiCMOS. BiCMOS 100K SOG arrays with 100-200MHz capability can be purchased from various vendors. BiCMOS microprocessors are starting to emerge from the lab and into production. Analog BiCMOS capabilities are being exploited in applications such as mobile communication. All in all, BiCMOS has been demonstrated to provide CMOS power and densities at bipolar speeds. At a given technology level, BiCMOS out-performs CMOS by a factor of 1.5-2.0X; 0.81i BiCMOS exceeds the performance of 0.5µm CMOS. So, why hasn’t BiCMOS taken over? Even though every major semiconductor company now boasts some form of BiCMOS technology, its relative process complexity keeps cost stubbornly high. It has also taken the circuit and system designers the full decade to learn how to best exploit BiCMOS, and we’re still learning. Commercial CAD tools, while making significant progress, remain inadequate at the higher levels of abstraction. Finally, the role of BiCMOS in a reduced power supply environment is controversial.