Active RFID tags combine LF wake up and 2.4 GHz communication

February 27, 2013 // By Julien Happich
Ams and Premo have developed an RFID system with active tags that includes the AS3940 2.4 GHz transceiver from ams on the base station, and a LF wake-up transmitter (15 kHz -150 kHz) based on a standard KGEA (Keyless Go Emitter Antenna) technology from Premo.

The active tags also rely on an ultra-low power MCU. The ams reference design uses a three-dimensional antenna system, with an antenna in each of the x, y, and z axes, Premo´s 3DC1515 Cap at 7.2 mH, feeding one of the device's inputs. This solution extends the use of the emitter antennas and the 3D antenna to the field of active tags. The data are not transmitted in low frequency but UHF with a higher bandwidth and transmission capacity; the major problem of active tags, the battery life, can be solved. The design allows the active tags to operate for three years with a small CR2032 coin cell. Premo antennas work in resonance or high tuning achieving high sensitivity and selectivity (High Q).

The circuit can be activated with a low power pulse signal and low frequency, then it automatically turns off or turns for the same procedure (change to LF reception mode). The use of 3DCoils ensure the active module work regardless of its spatial orientation as ensures that cross section brought to the field in LF is always maximum. All the components of the kit have been AECQ200 qualified. Premo offers a RFID designer kit with a set of receiver antennas with free refill service and an emitter antenna kit.