A Low Additive Noise Interference Canceller For High Sensitivity Applications

A canceller is designed to suppress undesired interference in an 802.11b WLAN radio from a Bluetooth radiator operating close to it. The design utilizes 0.18 mu m CMOS IC technology. The system consists of a core that emulates the interference-coupling channel between the two radios by time domain amplitude and phase alignment, and filtration. This is controlled by an adaptive loop. Using low noise design principles, the canceller core maintains a low output noise power spectral density of -173 dBm/Hz at the center frequency of the WLAN band. The consequent degradation of WLAN receiver sensitivity is 2.7 dB while achieving at least 15 dB of interference suppression. The canceller core dissipates 20mW of power.