Low noise wideband monotonically raising gain active equalizer in SiGe BiCMOS for phased arrays

In this brief, a wideband low noise active equalizer is presented that is implemented by utilizing SiGe BiCMOS technology, and packaged by in-house Au-stud bump flip-chip bonding. An amplification and filter stages are integrated to result in a gain profile, which is monotonically increasing over frequency. This is enabled by favouring a high cut-off frequency for the amplifier’s small-sized HBTs higher than the band of interest. Cascading the band select filter with the amplifier, enables the desired 50 Ω matching throughout 70 % of fractional bandwidth (BW). A Rogers 5870 substrate is utilized to flip the chip by in-house Au-stud bumps capability. A conductive epoxy is used for the bump and copper transition. The active equalizer achieves 10.83 dB peak gain with + 2.03 dB/BW of a linear slope between 5-to-13 GHz. Its measured noise figure is 3 dB at peak gain, after de-embedding the PCB transmission lines. The design's output compression point is –3.15 dBm while dissipating 46 mW of power in 1 mm 2 area. To the best of authors’ knowledge, the active equalizer has the highest gain-NF product and gain slope features among similar works

A highly linear SiGe BiCMOS Gilbert-cell based downconversion mixer for 5G applications

In this brief a high linearity, low loss, downconversion mixer requiring low LO drive power is presented for use in 5G beamforming applications. The emitter degenerated Gilbert-cell mixer with a four-way power combiner, baluns, and output filter is implemented using a 130-nm SiGe BiCMOS technology. The measured input 1-dB compression point of the fully integrated mixer is 6.4 dBm with a conversion gain of -12.9 dB. The mixer consumes 29.7 mW during small-signal operation and has a core area of 0.99 mm2. The relatively low loss and high linearity performance of the core mixer makes it uniquely suitable for use in 5G receivers

Dominant clade-featured SARS-CoV-2 co-occurring mutations reveal plausible epistasis: An in silico based hypothetical model

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into eight fundamental clades with four of these clades (G, GH, GR, and GV) globally prevalent in 2020. To explain plausible epistatic effects of the signature co-occurring mutations of these circulating clades on viral replication and transmission fitness, we proposed a hypothetical model using in silico approach. Molecular docking and dynamics analyses showed the higher infectiousness of a spike mutant through more favorable binding of G614 with the elastase-2. RdRp mutation p.P323L significantly increased genome-wide mutations (p \u3c 0.0001), allowing for more flexible RdRp (mutated)-NSP8 interaction that may accelerate replication. Superior RNA stability and structural variation at NSP3:C241T might impact protein, RNA interactions, or both. Another silent 5′-UTR:C241T mutation might affect translational efficiency and viral packaging. These four G-clade-featured co-occurring mutations might increase viral replication. Sentinel GH-clade ORF3a:p.Q57H variants constricted the ion-channel through intertransmembrane–domain interaction of cysteine(C81)-histidine(H57). The GR-clade N:p.RG203-204KR would stabilize RNA interaction by a more flexible and hypo-phosphorylated SR-rich region. GV-clade viruses seemingly gained the evolutionary advantage of the confounding factors; nevertheless, N:p.A220V might modulate RNA binding with no phenotypic effect. Our hypothetical model needs further retrospective and prospective studies to understand detailed molecular events and their relationship to the fitness of SARS-CoV-2