2–4 GHz Q-tunable LC bandpass filter with 172-dBHz peak dynamic range, resilient to +15-dBm out-of-band blocker

This paper presents a new Q-enhancement LC bandpass filter capable of 2.25~4.5 GHz frequency tuning range with independent Q control from 3 to 150. The BPF adopts both current-mode and voltage-mode drivers for more flexible operation in the intractable noise-linearity tradeoff space. A dual varactor inverse (DVI) control method is proposed to suppress varactor nonlinearity. Also, the BPF employs a dynamic negative resistance circuit that introduces a gain peaking when the filter output reaches 1-dB gain compression point, extending the P1db input power and therefore increasing the high power handling capability. The circuit is implemented in a 0.13 μm SiGe BiCMOS process. Measurement results show 9~-8 dBm of maximum IP1db, 10~18.5 dB of minimum NF, resulting in 146.5-172 dB Hz of normalized dynamic range when Q varies from 3 to 150 at f_c=3.25 GHz. The BPF consumes 13-20 mA from 3.3 V supply. Chip size is 0.7×0.68 mm².