CMOS-based UWB bandpass filter with in-band interference cancellation

This paper addresses the issue of in-band interference encountered where an Ultra-wideband (UWB) receiver is deployed in the vicinity of a wireless local area network (WLAN). The aim is to propose an original and compact UWB bandpass filter (BPF) with a notched band to mitigate the WLAN interference namely, the 5.2 and 5.8 GHz frequencies. The electrical model of the BPF has been synthesized using Hourglass function. The notch was integrated by cascading the BPF with a rejection cell to cancel the undesired band (5-6 GHz). The final circuit has been implemented in 0.18-μm CMOS technology and the simulation exhibits good performance, i.e., enhanced selectivity, large bandwidth covering the entire frequency range (3.1-10.6 GHz), avoidance of WLAN interference since the 5-6 GHz band is suppressed, good matching and flatness in the desired band, as well as small variation group delay. Besides of these interesting features, the final circuit of proposed notched UWB BPF is found optimized which can lead to compact size chip.