Fully isotropic electro-magnetic sensor for smartphones

The 1.65mm height target has been the biggest challenge during the last two years. It was achieved by a joint ecosystem development effort between BQ, UC3M University and Premo. The entire project was under the scope of a CDTI-Spain (Centre for the Development of Industrial Technology) research project called ASUMP.

This is a true ultra low-profile sensor with a 12x14mm footprint and a 1.65mm maximum height that is able to be integrated into ultra-thin devices such as SmartCard-type key fobs, traditional automotive key fobs, special miniaturised key fobs (sport keys), Smartphones (to be used as a digital key with the same user experience of current PKE access), and other devices such as hand-held controllers where EMMT (electromagnetic motion tracking technology) is used for 6DoF applications (real high- precision motion-tracking systems with no limitations in terms of line of sight, ultra-low latency, low power consumption, etc.).

With the new 3DC14EMR-ULP family, it is possible to ‘float’ the coil in the PCB resulting in a true height of less than one millimetre with a standard 0.6 to one millimetre thick PCB.

This new 3DC ULP version also provides greatly increased sensitivity. Inductance values of each axis (x, y and z) are 4.77mH / 6.3mH / 10.5mH, allowing the coil to achieve sensitivities of 95 / 100 / 80 mV/A/m as a minimum per axis. 

This level of sensitivity makes the part performance at the same level as today’s market standard for taller and larger parts. With such low profile and high sensitivity, this 3DC ULP is the best solution in terms of performance against size volume used.

Cutting edge Smartphones include multiple communication antennas integrated, enabling connectivity capabilities in single device like never before: GPS, Galileo Sat, WiFi, 3G, 4G, 4G LTE, 5G, NFC, BT, BLE, Qi Wireless Charging. Low Frequency communication with magnetic fields (RFID, in kHz frequency range) has been a connectivity and positioning technology widely used in automotive car access systems for many years. 

Creating a passive entry system using only today’s Smartphone capabilities (BTLE/NFC) is possible but have handicaps that can be overcome by LF technology. To achieve the same user experience level as current state-of-the-art passive entry key fobs, the inclusion of a low frequency magnetic field antenna in the Smartphone is mandatory. 

Premo’s latest innovation, the 3DC14ULP, is a specific development focused on this application and device: the Smartphone. Lowering the profile was a key factor to the success of this integration and allows the use of digital keys for controlling access to their vehicles.

This part includes three-axis (x, y and z) windings 100% encapsulated in epoxy to provide full functionality for wakeup and 6DoF position/orientation even with movement tracking. Premo provides multiple versions of fully isotropic 3DCoil configurations to provide solutions for trimmed and non-trimmed performances.