Compact On-Chip Millimeter-Wave Bandpass Filters with Meandered Grounding Resonator in 0.13-μm (Bi)-CMOS Technology

In this study, an ultra-compact meandered grounding resonator is proposed to design two millimetre wave bandpass filters (BPFs) in a standard 0.13-µm silicon-germanium (Bi)-complementary metal oxide semiconductor (CMOS) technology. The fundamental second-order prototype, namely BPF-I, consists of a pair of proposed resonators and a pair of grounded metal-insulator-metal (MIM) capacitors. To better understand the principle of the second-order BPF-I, an equivalent LC-circuit model and theoretical analysis method are presented in this study. Based on BPF-I, the second-order BPF-II is proposed by adding the additional two pairs of MIM capacitors to improve the frequency selectivity, by means of introducing a transmission zero at lower stopband. Finally, both of the two second-order BPFs are fabricated. The measured results show a good agreement with the full-wave simulation results. The insertion loss of the first BPF-I is 1.79 dB at the centre frequency of 46.6 GHz, and the fractional bandwidth is up to 96.5%. The second BPF-II has a centre frequency at 46.8 GHz with a fractional bandwidth of 94.1%. The minimum insertion loss is 2.08 dB and the lower stopband attenuation is up to 42.7 dB. Moreover, the die sizes of the two compact BPFs, excluding the test pads, are only 0.0197 mm2 (0.104 × 0.190 mm2).