Inductive antenna coupling
This invention pertains to the connection between a radio frequency circuit and its antenna. Miniaturization of radio frequency integrated circuits has made attaching these circuits to their antennas increasingly difficult and costly. This invention uses magnetic coupling, as performed in transformers, between circuits and antennas as a practical solution to reduce cost and effort in attaching the two sides as well as to protect the circuit against electrostatic discharge. Furthermore a simple pre-assembly testing methodology is accounted for as an additional benefit of the method.
1. An RF tag comprising:
a radio frequency integrated circuit located on a an integrated circuit substrate; and
an antenna located on an antenna substrate, the RF tag further including a transformer having a first inductor on the circuit substrate and a second inductor on the antenna substrate, wherein the first and second inductors are configured to inductively couple RF signals between the radio frequency integrated circuit and the antenna;
wherein the first inductor comprises a plurality of first inductors and wherein the second inductor comprises a plurality of second inductors, the RF tag being configured such that any of the first inductors could couple to any of the second inductors.
2. The RF tag of claim 1 wherein at least two of each of the plurality of first inductors and the plurality of second inductors are concentric.
3. The RF tag of claim 1 wherein the inductive coupling acts as ESD protection for the integrated circuit substrate.
4. The RF tag of claim 1 wherein the radio frequency circuit supports multiple radio bands.