A micromachined V-band CMOS bandpass filter with 2-dB insertion-loss

A low-insertion-loss V-band CMOS bandpass filter is demonstrated. The proposed filter architecture has the following feature: the low-frequency transmission-zero (omega_z1) and the high-frequency transmission-zero (omega_z2) can be tuned by the series-feedback capacitor C_s and the parallel-feedback capacitor C_p, respectively. To reduce the substrate loss, the CMOS process compatible backside inductively-coupledplasma (ICP) deep trench technology is used to selectively remove the silicon underneath the filter. After the ICP etching, this filter achieved insertion-loss (1/S₂₁) lower than 3 dB over the frequency range of 52.5-76.8 GHz. The minimum insertion-loss was 2 dB at 63.5 GHz. To the authors' knowledge, this is the best result ever reported for a V-band CMOS bandpass filter in the literature.