Analysis and design of an interference canceller for collocated radios

An active interference cancellation scheme is presented to mitigate interference between Bluetooth and wireless local area network (IEEE 802.11 b) radios operating in close proximity. This method is extensible to other mutually interfering radio devices. A reference signal correlated to the original interferer is used to generate a cancellation signal by means of amplitude and phase alignment, and filtration. The filter employed emulates the coupling channel responsible for interference. An implementation of this procedure in 0.18-/mu m Si-complementary metal-oxide-semiconductor (CMOS) integrated-circuit (IC) technology is also presented. The circuits fabricated are tunable and are controlled by a closed-loop adaptive process including an error minimization method. The cancellation system designed achieves 15-30 dB of interference suppression for different cases. A total power of 14 mW is dissipated by the CMOS ICs designed.