A Low Power,High Sensitivity SiGe HBT Static Frequency Divider up to 90 GHz for Millimeter-Wave Application

A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.

Serum IgA,IgM,and IgG responses in COVID-19

Currently,detecting SARS-CoV-2 RNAs is a standard approach for COVID-19 diagnosis.However,there is an urgent need for reliable and rapid serological diagnostic methods to screen SARS-CoV-2-infected people including those who do not have overt symptoms.Most emerging studies described serological tests based on detection of SARS-CoV-2-specific IgM and IgG.1–4 Although detection of SARS-CoV-2-specific IgA in serum has been reported in few papers,5,6 analyses of IgA levels in a larger number of COVID-19 patients are still lacking.

Decline of SARS-CoV-2-specific IgG,IgM and IgA in convalescent COVID-19 patients within 100 days after hospital discharge

Dear editor,The 2019 novel coronavirus(later renamed as SARS-CoV-2 in February 2020)infected over 12 million people globally by early July 2020,causing mild to severe COVID-19 in millions.Monitoring the levels of antibodies such as immunoglobin(Ig)G,M and A that are specific to SARS-CoV-2 and present in the blood provides not only an alternative method for diagnosing SARS-CoV-2 infection(including asymptomatic carriers),but also a simple way to monitor immune responses in convalescent patients or after vaccination.A high and persistent level of antibodies specific to SARS-CoV-2,especially those that can bind to and neutralize the virus,would be a strong indication that an immunized host could resist to SRAS-CoV-2 infection.Currently,there are no effective drugs to specifically prevent or cure SARS-CoV-2 infection;therefore,host immune responses and antibody-based therapeutics will continue to play important roles in combating and later preventing COVID-19.