Mixing signals but not messages

Mixed-signal technologies which combine both analog and digital functionality are vital to the automotive industry because cars are full of signals that need sensing, amplifying and converting – all analog functions. At the same time, complex control and computational functions provided by digital circuitry are needed to improve the total driver experience.

Automotive Industries (AI) discusses the technology with Christine King, president and CEO of AMI Semiconductors (AMIS).

King: Mixed-signal technology has been used for many years in the automobile industry. An early example is anti-skid braking systems, where the mixed-signal circuit “captures” the sensor signal, converts it to a digital signal then compares it to millions of patterns in its computer memory. The brakes are then applied in the most effective way to achieve the shortest possible stopping distance without loss of control of the vehicle.

AI: Where is the future of mixed-signal technology?

King: Mixed-signal technology is growing quickly in the automotive industry. Car manufacturers are recognising that the features enabled by the technology not only add safety and convenience, but can also help differentiate their car from its competitors.

Examples of the latest applications include: automatic wiper systems, tire pressure monitoring systems, GPS navigation systems and “bending” headlights. All of these programmable examples are enabled by AMI Semiconductor’s ability to combine microcomputers and analog on a single chip.

In addition, circuits often need to “talk” to each other within the car. In recent years, the car area network (CAN) standard has become the standard interface, allowing information transmission at one million bits per second (1Mbits/sec) around the wiring loom. In the future, optical fiber will replace the wiring loom reducing weight, and enabling communication at around 10 times the speed. This will allow video to be distributed around the car, and also make drive-by-wire a possibility. The Flexray standard is currently being defined for these applications.

AI: What are you doing to ensure that the systems you design can be maintained and adjusted once they are fitted to the vehicles?

King: Programmable systems are easy to update after installation. An updated program can be installed in the computer memory so that any new safety or convenience feature can be enabled. This allows the car manufacturer to easily upgrade the car specification, without having to change the hardware. Many car manufacturers are taking advantage of this capability to plan their feature upgrades over the model life.

AMIS is one of only two manufacturers that combine high voltage analog, dense digital logic and cost effective “Flash” memory, all specified and characterized for high temperature operation, on a single chip. This enables the car manufacturer to easily upgrade safety capabilities and adjust for different market and climate conditions.