
Integrating magnetoresistive sensors with BiCMOS circuits
In the course of R&D, the company invested in high precision thin film deposition tools and equipment within an advanced BCD wafer manufacturing facility, where high-volume manufacturing is under way.
The new AxMR technology platform integrates high sensitivity MR (magnetoresistive) sensor elements and high precision BiCMOS circuits on a single silicon integrated circuit, combining Allegro’s automotive grade, high voltage wafer processes with high accuracy, automotive grade MR sensors. Designed to fit into industry standard IC packages, the AGMR technology was designed to withstand the rigorous automotive under hood environment. The technology is thermally stable to greater than 150°C, even in the presence of large magnetic fields.
Explaining the reasoning behind this new development, Michael Doogue, Vice President of Business Development said “Hall-effect technology meets the needs of many applications in Allegro’s target markets, but there are certain applications, particularly in the areas of ADAS and high efficiency vehicles, where xMR technology offers more elegant solutions relative to Hall technology”.
“In these applications, Allegro’s xMR ICs provide more accurate measurement data, enable more favorable mechanical placement of a sensor IC within a mechanical system, or create smaller form factor solutions with a lower overall cost.”
Allegro’s first generation AxMR ring-magnet Speed Sensor ICs are already in production at a leading Tier 1 automotive supplier of wheel speed sensors. These ICs rely on Allegro’s patented signal processing algorithms to meet the needs of both standard and direction detection wheel speed sensor platforms. GMR technology enables low jitter rotational speed measurements that are not possible with Hall effect ICs.
The company is actively developing monolithic back-biased GMR sensors for advanced engine management and transmission gear speed sensing applications, where the same low jitter measurements and large air gap performance are essential for advanced powertrain system operation.
Allegro also recently released its first GMR based current sensor IC, a device capable of resolving currents of less than 1mA, and has plans to leverage MR technology to further disrupt the market for monolithic current sensor ICs.
Allegro MicroSystems – www.allegromicro.com
