In the early days of analog ICs, chip designers had a large arsenal of circuit elements that let them create products with exceptionally high performance. Over time, to keep analog IC prices competitive, analog process technologies followed the lead of digital CMOS. Analog chip designers then found themselves with fewer and fewer magic analog bullets they could use to design new products. This has been particularly hard on engineers who design "industrial" mixed-signal systems, because they now find themselves squeezed between the relatively high-voltage world of their sensors and actuators and the ever diminishing operating and threshold voltages of successive CMOS generations.
In a welcome countertrend, analog/mixed-signal IC companies are developing new process technologies that permit mixing voltages on a single die as well as combinations of CMOS, high-voltage MOS, and high- and low-voltage bipolars. As a result, analog chip designers are again expanding their arsenals. Competition will continue to encourage innovation and improve performance.
What, exactly, are "industrial" analog and mixed-signal applications?
Generally, the term encompasses factory automation and process control, instrumentation (both automatic test equipment and bench gear), medical products (ranging from MRI and CAT-scan equipment to portable diagnostic instruments and personal testers for glucose and fever temperature), and automotive (airbags, ABS, ignition control, active suspension, and tire-pressure monitoring). Taken together, these applications represent more than 30% of the market for data converters and signal-conditioning electronics.
What's the problem with using advanced CMOS-based analog chips in industrial designs?
Engineers who create these systems are squeezed between the relatively high, often differential voltages at which their sensors and actuators operate and the voltage limits of the latest CMOS. Consequently, they've had to add more and more signal conditioning built on older technologies on either side of their converters and control systems. This approach is expensive and power-hungry, and it wastes board space.
Click here to download the PDF version of this entire article.