According to a press release from ams, the automotive supplier chose the AS3914 because it enables reliable NFC coupling even when mounted in close proximity to sheet metal. The device also offers lower average power consumption than competing NFC reader.
For contactless key applications, the Marquardt NFC module is mounted inside the door handle, and also in the car’s center console (inside the cabin). In the door handle, the 13.56MHz module couples with any standard NFC card (tag) or tag emulator, such as a mobile phone, smart watch or tablet. The driver simply has to touch their device to the handle; the system has an operating range of around 4cm. On recognizing the authorized tag’s identity, the module instructs an electronic control unit (ECU) to unlock the car.
A second module in the center console must again perform contactless coupling with the driver’s tag before enabling the car to start.
The Marquardt module will be used in the next generation of production vehicles from one of Europe’s premium car makers, the company said without however identifying the OEM.
In the door handle application, the NFC reader has to operate in conditions hostile to RF transmissions: the sheet metal of the car door acts as an unwanted antenna, deflecting much of the RF energy emitted by the reader. Marquardt’s design engineers found that the AS3914 offered far more predictable and reliable performance in these conditions than other NFC reader ICs did. This is because the AS3914 combines high RF output power of up to 1W, high sensitivity, and a unique Automatic Antenna Tuning (AAT) feature which compensates for attenuating and distorting effects, such as those caused by the metal surfaces in vehicles.
Using the AS3914, Marquardt is able to achieve a range from the door handle of 4cm in almost all operating conditions, even in car designs which have a chrome metal overlay on the plastic door handle. This range is