220GHz低噪声放大器研究

基于IHP锗硅BiCMOS工艺,研究和实现了两种220 GHz低噪声放大器电路,并将其应用于220 GHz太赫兹无线高速通信收发机电路。一种是220 GHz四级单端共基极低噪声放大电路,每级电路采用了共基极（Common Base, CB）电路结构,利用传输线和金属-绝缘体-金属(Metal-Insulator-Metal, MIM)电容等无源电路元器件构成输入、输出和级间匹配网络。该低噪放电源的电压为1.8 V,功耗为25 mW,在220 GHz频点处实现了16 dB的增益,3 dB带宽达到了27 GHz。另一种是220 GHz四级共射共基差分低噪声放大电路,每级都采用共射共基的电路结构,放大器利用微带传输线和MIM电容构成每级的负载、Marchand-Balun、输入、输出和级间匹配网络等。该低噪放电源的电压为3 V,功耗为234 mW,在224 GHz频点实现了22 dB的增益,3 dB带宽超过6 GHz。这两个低噪声放大器可应用于220 GHz太赫兹无线高速通信收发机电路。     

Hydraulic linkage of a storm water tank to a karst spring (Gallusquelle)

Grundwasser - A significant proportion of the global water supply is ensured by karst aquifers. However, these are often highly vulnerable to contamination. A storm water tank...     

An integrated 8-12 GHz fractional-N frequency synthesizer in SiGe BiCMOS for satellite communications

We present an integrated fractional-N low-noise frequency synthesizer for satellite applications. By using two integrated VCOs and combining digital and analog tuning techniques, a PLL lock range from 8 to 12 GHz is achieved. Due to a small VCO fine tuning gain and optimized charge pump output biasing, the phase noise is low and almost constant over the tuning range. All 16 sub-bands show a tuning range above 900 MHz each, allowing temperature compensation without sub-band switching. This makes the synthesizer robust against variations of the device parameters with process, supply voltage, temperature and aging. The measured phase noise is ?87 dBc/Hz and ?106 dBc/Hz at 10 kHz and 1 MHz offset, respectively. In integer-N mode, phase noise values down to ?98 dBc/Hz at 10 kHz and ?111 dBc/Hz at 1 MHz offset, respectively, were measured.     

Vorkommen und Verhalten eines Arzneimittels (Clofibrinsäure) im Grundwasser

As to nowadays knowledge drugs in groundwater originate from anthropogenic input by urine and production residue. Clofibric acid, a blood lipid regulator is one of the human drugs already detected in groundwater and drinking water with concentrations of up to 7300 ng/l. Recent investigations indicate, that some drugs are insufficiently or not degraded by sewage treatment or by drinking water production. Groundwater contamination is likely to be due to leaky sewage systems, influent streams and bank infiltration. The distribution of clofibric acid beneath the sewage farms south of Berlin shows the high mobility of this contaminant. Nevertheless, results indicate that there is no correlation between the concentrations of clofibric acid and physico-chemical parameters, groundwater constituents nor sediment material. First results of a column experiment show that clofibric acid is transported with tracer velocity, although some variations in concentration of clofibric acid occur. Again, no correlation between clofibric acid and pH, oxygen content nor the concentration of groundwater constituents has been found whereas a possible dependence of the redox potential on clofibric acid was observed. During the column experiment no sorption processes could be identified, but there were hints for a degradation of clofibric acid.     

Hydrogeologie und Hydrologie der Halbinsel Darß – Zwischen Meerwasserintrusion und Landnutzung

Grundwasser - Die Halbinsel Darß in Mecklenburg-Vorpommern ist aufgrund ihrer rauen Schönheit und der Küstenlage ein beliebtes Urlaubsgebiet. Als Teil des Nationalparks Vorpommersche...     

Passive Probennahme mit Keramikdosimetern: M?glichkeiten und Grenzen der Einsetzbarkeit

As a result of a railway-accident, the aquifer in Elsterwerda (southern Brandenburg, Germany) has become contaminated with unleaded fuel. To monitor groundwater quality at this site, several ceramic dosimeters were installed in selected observation wells. The adsorber material in the dosimeters was conditioned to sample benzene, toluene, ethylbenzene and xylene. The dosimeters were installed between two regularly scheduled groundwater sampling events. Active and passive sampling results showed considerable differences in concentration in some cases. In addition to the diameter of the observation well, the main reason for the difference was a high dependency of passive sampling on the hydraulic connection between the observation wells and the aquifer. As a result of the comparison of active and passive sampling as well as considering additional site investigation data related to the spatial spreading of the contamination, it was possible to determine the hydraulic connection between the well and aquifer for the investigated wells. Hence, the application of ceramic dosimeters at Elsterwerda was not only suitable to acquire depth-dependent concentrations, but also to obtain information on the physical and hydraulic condition of the observation wells. However, rather limited additional information can be gained from the application of ceramic dosimeters at sites where there is no a priori information on the hydraulic connection of a well or on the depth-dependent distribution of the contamination.