EMI suppression for near field links

For near field communication, inductive coils coupled to each communication circuit are brought close together such that there is an inductive coupling between the two coils. The data signal may then be relayed between the two circuits without any direct connection between them. However, the system is susceptible to common mode noise (e.g., environmental EMI). In addition to a pair of "active" coils for transmitting and receiving data, a pair of "passive" coils proximate to the pair of "active" coils is provided, which are only used to detect ambient EMI. The EMI signal detected by the passive coil is processed by a noise detector/processor, which then controls the transmitter and/or receiver to at least partially compensate for the detected EMI signal. The transmit power or receiver threshold may be controlled by a noise detector/processor to improve the signal-to-noise ratio, or other compensation techniques may be used. 对于近场通信，将耦合到每个通信电路的电感线圈靠近在一起，以使两个线圈之间存在电感耦合。然后可以在两个电路之间中继数据信号，而无需在它们之间进行任何直接连接。但是，系统容易受到