Several key techniques for a PLL-type frequency synthesizer for WLAN receivers are studied. Its structure is analyzed and the main parameters are proposed. A monolithic LC-tuned voltage controlled oscillator （LCVCO）...Several key techniques for a PLL-type frequency synthesizer for WLAN receivers are studied. Its structure is analyzed and the main parameters are proposed. A monolithic LC-tuned voltage controlled oscillator （LCVCO） with low phase noise is fabricated with TSMC 0.18μm RF （radio frequency） CMOS technology. The measured phase noise is - ll7dBc/Hz at 4MHz off the center frequency of 4. 189GHz. A down-scaling circuit with low power dissipation was fabricated in a TSMC 0.18μm mixed-signal CMOS process. The measured results show that the IC can work well under a 1.8V power supply. Its total power dissipation is only 13mW.展开更多
The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous ...The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous observations of equatorial electrojet(EEJ) strength,geomagnetic activity index,and solar flux index during the 2002-2003 sudden stratospheric wanning(SSW) event.Analysis of these observations indicates the existence of a large-scale quasi 16-day periodic meridional movement in both EIA crests,and also reveals a strong correlation between the quasi 16-day oscillation in geomagnetic latitudes of the EIA crest and EEJ strength.The latitude of the northern/southern EIA crest and the EEJ strength indicate that obvious synchronous periodic oscillations were in-phase in the northern and southern hemisphere when the SSW occurred.In addition,it is also found that both the EIA crest location and amplitude of the periodic movement of the EIA locations exhibit hemispheric asymmetry.The amplitude of the periodic movement of the EIA location in the southern hemisphere is larger than that of the northern hemisphere,and the southern EIA crest is further off from the equator than the north one.Understanding these asymmetries requires a combination of mechanisms that involve at least trans-equator meridional winds and the position of a sub-solar point;however,potential disturbances in neutral winds associated with the SSW may additionally complicate the equatorial ionospheric dynamics.展开更多
文摘Several key techniques for a PLL-type frequency synthesizer for WLAN receivers are studied. Its structure is analyzed and the main parameters are proposed. A monolithic LC-tuned voltage controlled oscillator （LCVCO） with low phase noise is fabricated with TSMC 0.18μm RF （radio frequency） CMOS technology. The measured phase noise is - ll7dBc/Hz at 4MHz off the center frequency of 4. 189GHz. A down-scaling circuit with low power dissipation was fabricated in a TSMC 0.18μm mixed-signal CMOS process. The measured results show that the IC can work well under a 1.8V power supply. Its total power dissipation is only 13mW.
基金supported by the National Natural Science Foundation of China(Grant Nos.41274156, 41464006 & 41674157)Guangxi Natural Science Foundation(Grant No.2014GXNSFAA118282)+1 种基金L.Goncharenko and S R.Zhang have been supported through US National Science Foundation(Grant No. AGS-1132267)the Haystack Observatory was also supported through a cooperative agreement(Grant No.AGS-1242204) between the US National Science Foundation and MIT
文摘The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous observations of equatorial electrojet(EEJ) strength,geomagnetic activity index,and solar flux index during the 2002-2003 sudden stratospheric wanning(SSW) event.Analysis of these observations indicates the existence of a large-scale quasi 16-day periodic meridional movement in both EIA crests,and also reveals a strong correlation between the quasi 16-day oscillation in geomagnetic latitudes of the EIA crest and EEJ strength.The latitude of the northern/southern EIA crest and the EEJ strength indicate that obvious synchronous periodic oscillations were in-phase in the northern and southern hemisphere when the SSW occurred.In addition,it is also found that both the EIA crest location and amplitude of the periodic movement of the EIA locations exhibit hemispheric asymmetry.The amplitude of the periodic movement of the EIA location in the southern hemisphere is larger than that of the northern hemisphere,and the southern EIA crest is further off from the equator than the north one.Understanding these asymmetries requires a combination of mechanisms that involve at least trans-equator meridional winds and the position of a sub-solar point;however,potential disturbances in neutral winds associated with the SSW may additionally complicate the equatorial ionospheric dynamics.
