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In this letter, a packaged bandpass filter (BPF) with a compact size of $1.5 \times 1.5 \times 0.315$ mm3 operating at 28 GHz is proposed. This BPF is implemented based on a multilayers printed circuit board (PCB) fabrication process with ultra-thin substrate. With the packaged configuration, the filter can not only reduce the circuit size and component insertion loss, but also eliminate the effect of electromagnetic (EM) radiation. To verify the mechanisms mentioned above, a packaged millimeter-wave (mm-wave) BPF with three transmission zeros is designed and fabricated. The measured results show that the proposed BPF has the merits of low insertion loss, high selectivity, and compact size. Meanwhile, this BPF can suppress harmonics with a rejection level of more than 24 dB up to 110 GHz. With these merits, the proposed BPF is attractive for 5G mm-wave application. [ABSTRACT FROM AUTHOR]

This article proposes a quad-core millimeter-wave (mm-wave) oscillator using E-M mixed-coupling resonance boosting. The mixed-coupling resonator is introduced to generate four reconfigurable resonances. The magnetic coupling and electric coupling are achieved by the symmetrically coupled transformer and coupling capacitor, respectively. A 2-D mode switch array is introduced to couple the quad-core and achieve the quad-mode switching without degrading the performance of the selected mode. Therefore, the reduction of phase noise and the extension of tuning range are achieved simultaneously. Meanwhile, the digitally controlled tail-resistor array is used to optimize the flicker noise up-conversion in wideband. Prototyped in 40-nm CMOS, the proposed oscillator exhibits a 73.2% tuning range from 18.6 to 40.1 GHz. The best phase noise at 1-MHz offset is −108.5 dBc/Hz, corresponding to an figure-of-merit (FoM) of 184.4 dBc/Hz and FoMT of 201.7 dBc/Hz. The variation range of FoM over the whole frequency range is 3 dB. The 1/ƒ3 phase noise corner is 220–620 kHz. [ABSTRACT FROM AUTHOR]

In this letter, a compact wideband bandpass filter (BPF) with a wide stopband is proposed based on the substrate integrated defected ground structure (SIDGS) and folded stepped-impedance resonator (FSIR). Such a SIDGS resonator can not only allocate a specific resonance with compact size but also introduce the different harmonic positions compared with a traditional microstrip line resonator. Meanwhile, due to the discrepant harmonic positions of proposed SIDGS and FSIR, a wide stopband response can be achieved using a compact stacked-coupled scheme. To verify the mechanism, a miniaturized wideband BPF operating at 1.69 GHz (i.e., ƒ0) is implemented and fabricated. A measured wide stopband up to 11.8 ƒ0 with a 20-dB rejection level is achieved. [ABSTRACT FROM AUTHOR]

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 single-band 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 dual-band 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. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive synthesis using the particle swarm optimization (PSO) for implementations of resonator-coupled filters is proposed. The coupling matrix of in-band filtering response is achieved and optimized by the PSO-based synthesis. Meanwhile, the stopband coupling matrix of the filter is predicted based on the combination of extra resonant nodes representing stopband spurious and parasitic effect of input/output ports. In addition, an enhanced accurate prediction of filter performance is calculated by the proposed approach, considering the practical fabrication tolerance on filter design. To verify principles mentioned earlier, various resonator-coupled filters are implemented. The calculation, EM-simulation, and measurement of filters show good agreements in both passband and stopband. [ABSTRACT FROM AUTHOR]

In this letter, a compact wideband phase shifter using a microstrip self-coupled line and a broadside-coupled microstrip/CPW (BCMC) structure is proposed for multiphase feed-network. With a uniform phase reference, such a phase shifter can achieve multiphase responses by adjusting instinct self- and broadside couplings for constant phase shifts within a wideband. Then, with the combination of proposed phase shifters and a microstrip Wilkinson power divider, a multiphase feed-network can be implemented. To verify the mechanisms mentioned earlier, a wideband feed-network is fabricated with measured multiphase responses (i.e., 0°, 5.625°, 11.25°, 22.5°, 45°, 90°, and 180°) and maximum insertion loss of 1.57 dB from 1.7 to 2.3 GHz. [ABSTRACT FROM PUBLISHER]