In this article, two types of substrate-integrated defected ground structure (SIDGS) resonant cells with wide upper stopband and low radiation loss are presented for filter implementation. Such SIDGS resonant cells are composed of two dissimilar DGSs surrounded by the bottom ground and metal-vias, which cannot only introduce wide stopband with low radiation loss but also be flexible for integration. Based on the aforementioned SIDGS resonant cells, single-and dual-band bandpass filters (BPFs) are designed and fabricated. The singleband BPF centered at 2.40 GHz exhibits an ultrawide upper stopband up to 19.7 GHz with a rejection level of 31 dB, whereas the measured stopband total loss (i.e., including radiation, metal, and substrate loss) remains about 30% up to 19.3 GHz. The dualband BPF operated at 2.10 and 3.78 GHz exhibits an ultrawide upper stopband up to 17.8 GHz with a rejection level of 23 dB, whereas the measured stopband total loss is less than 16% up to 11.4 GHz.
In this article, a 22.9-38.2-GHz dual-path noisecanceling low noise amplifier (LNA) is proposed, which can achieve a low noise figure (NF) by reducing the noise of both paths. Such LNA consists of one common gate (CG) amplifier with one three-stage transformer, one resistive feedback common-source (CS) amplifier, and two amplitude-adjusting amplifiers. The three-stage transformer is used in the CG amplifier to provide gain-boosting, noise-reducing, and wideband inter-stage matching operation, simultaneously. Meanwhile, amplitude-adjusting amplifiers with reconfigurable phase-tuning lines are utilized in both paths to optimize the noise-canceling performance. To verify the aforementioned principle, a dualpath noise-canceling LNA is implemented and fabricated using a conventional 28-nm CMOS technology. The proposed LNA consumed 18.9 mW under a 0.9-V supply. The measured NF is 2.65-4.62 dB within the operating frequency range of 22.9-38.2 GHz, while the peak gain is 14.5 dB. The in-band input 1-dB compression point (IP 1 dB ) and input third-order intercept point (IIP3) are −13.2 to −6.6 and −3.6 to 3.2 dBm, respectively.
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