1-dB insertion-loss 1∼14.3 GHz ultra-wideband bandpass filter using standard 0.18 μm CMOS technology

A low insertion-loss ultra-wideband (UWB) bandpass filter (BP-filter) with two finite transmission zeros (f_z1 and f_z2) at high-frequency stop-band by 0.18 μm CMOS technology was demonstrated. F_z1 (the lower frequency one) and f_z2 can be tuned individually by the shunt branch (L₂, R_s2, C₃ and C₄+C_p2) and the series inductor (L₁, R_s1 and C_p1), respectively. The micro-stripline (MSL) interconnection lines as well as the spiral inductors were implemented by the 2.34-μm-thick topmost metal (M₆) to minimize the resistive loss. This filter achieved insertion-loss (1/S₂₁) lower than 3 dB for frequencies 1~14.3 GHz, stop-band rejection better than 20 dB for frequencies higher than 20.4 GHz, and input return loss (S₁₁) better than -10 dB for frequencies 2.4-16.4 GHz. The minimum insertion-loss was 1 dB at 4.2 GHz. To our knowledge, this is the best result ever reported for a CMOS UWB BP-filter in the literature.