More safety – less dead victims: Freescale Semiconductor expands its Xtrinsic sensing portfolio with “intelligent” radar technology. Using Silicon Germanium (SiGe) instead of Gallium Arsenid (GaAs), the 77 GHz chipset enables vehicles to sense potential crash situations, claims the company.
“77 GHz is likely to be the European Union’s radar band of choice in 2013, with China and the United States expected to follow,” affirms Tom Deitrich, Senior Vice President and General Manager Cellular Products and RF, Analog & Sensor at Freescale Semiconductor. The company is now providing samples of 77 GHz integrated chipsets in SiGe technology. SiGe has become the standard for many wireless applications as consumer demand for low-power portable products continues to increase. Recently, SiGe has found increasing interest for emerging high-frequency markets, such as automotive radar.
Xtrinsic radar chipsets are manufactured in Freescale’s 0.18 μ BiCMOS technology and consists of a transmitter and a multi-channel receiver with an integrated phase-locked loop (PLL). Its technology allows a device to switch between long- and short-range functionality simply by issuing a serial peripheral interface (SPI) command. This enables the same radar module to be used for multiple safety systems, such as adaptive cruise control, headway alert, collision warning and mitigation. Long-range radar, used for adaptive cruise control and lane departure warnings, has long and narrow coverage directly in front and back of the car. Short-range radar, ideal for blind spot detection, pre-crash and stop-and-go applications, monitors the car’s immediate surroundings with a wide spatial view that covers shorter distances.
Accelerometers automotive active safety applications
Apart from the radar chipset, Freescale is expanding its Xtrinsic family some more: MMA6900Q and MMA6901Q are the accelerometers for advanced automotive active safety applications. Automobiles have included passive safety systems, such as airbags and seatbelts, for years to minimize injuries from crashes. Recently, the industry began incorporating intelligent active safety systems to help prevent accidents from occurring. Electronic stability control (ESC) is an example of an active safety system that proactively helps safeguard passengers through the use of multiple smart sensors that monitor the driving environment.
According to the U.S. National Highway Traffic Safety Administration (NHTSA), ESC could have prevented nearly one-third of all fatal car accidents. Therefore, NHTSA is mandating that most 2012 model year vehicles include this technology. ESC helps drivers maintain control of their vehicles by using high-performance, low-g two-axis sensors to measure the lateral and longitudinal acceleration of the vehicle. When sensors register potentially unstable driving conditions, the system sends data to the car’s engine and braking system to automatically assist the driver in maintaining vehicle control.
The accelerometers Xtrinsic MMA6900Q and MMA6901Q offer a wide range of sensing with high resolution. Designers are able to filter out extraneous signals, such as parasitic vibrations, that could potentially interfere with the vehicle’s lateral acceleration measurement. Both are based on high-aspect-ratio micro-electromechanical systems (HARMEMS) technology, a technology used for airbag sensing applications. Not only will this technology improve the robustness of the sensor, but HARMEMS technology provides over-damped mechanical response and a very good signal-to-noise ratio. Over-damped HARMEMS technology enables a high degree of immunity to high-frequency, high-amplitude parasitic vibrations – a key feature since active safety applications, like ESC, are typically installed in the vehicle cabin or under the hood.
For ESC applications, the higher signal-to-noise ratio combined with Freescale’s DSP-based signal chain is designed to provide a wide range and high sensitivity. The sensors packed in a 6 x 6 mm QFN are included in Freescale’s product longevity program, with assured supply for a minimum of 15 years.