This paper describes the fabrication and characterization of coplanar waveguides and low pass filters on thin dielectric membranes for D-band frequencies powered by transitions to rectangular waveguides. The membranes deposited from hexamethyldisilazane (HMDSN) were fabricated by removing the underlying silicon with micromachining techniques. Coplanar waveguides of various lengths based on these thin dielectric membranes have been fabricated and characterized as low-loss circuits for D-band frequencies. Two low pass filters with corner frequencies of 120 GHz and 170 GHz have been investigated, fabricated and characterized.
In this letter, we report on the record performance of GaAs-based heterostructure barrier varactors (HBVs) in tripler circuits. Both fabrication technique of planar Al/sub 0.7/Ga/sub 0.3/As/GaAs heterostructure barrier varactors (HBVs) and measurements of a corresponding tripler circuit are presented. Planar transmission lines on a thin dielectric membrane and flip-chip technique without air bridges provide reduced parasitic losses and, hence, higher tripler efficiency. Frequency tripler measurements have shown more than 1 mW at 450 GHz.
Several transitions from coplanar waveguide on thin dielectric membrane to rectangular waveguide have been investigated. The optimum transition structure turned out to consist of a coplanar-to-microstrip transition on membrane followed by a triangularly shaped microstrip probe performing the transition from microstrip line to rectangular waveguide. The taper between the coplanar and the microstrip transmission line as well as the shape of the microstrip probe has been optimized for D-band operation.
Abstract This ultrafiltration technique allows determination of free drug in 50 microL of serum. We ultrafiltered sera containing the following drugs--valproic acid (and its major metabolites), phenobarbital, diazepam, indomethacin, phenytoin, furosemide, and chloramphenicol--using both the commercially available micropartition system (MPS-1, Amicon), which requires a 200-microL sample, and our modified micro system, which requires only 50 microL. The value for the free fraction of each drug obtained in the two experiments agreed well. The smaller sample requirement makes the micro method particularly suited for pediatric samples and studies on small laboratory animals.
This paper describes the fabrication of coplanar waveguides on thin dielectric membranes. The membranes deposited from hexamethyldisilazane were fabricated by structuring the underlying silicon with micromachining techniques. A transition from membrane-based coplanar waveguide to silicon-based coplanar waveguide for Ka-band has been designed, fabricated and characterized. A transition from membrane-based coplanar waveguide to rectangular waveguide has been evaluated and realised for D-band.
The realization of a 150 GHz to 450 GHz tripler circuit based on a thin dielectric HMDS-N membrane is described. The design requires an integration of a GaAs-based heterostructure barrier varactor on a passive feeding structure based on a thin dielectric membrane, which is realized by thermocompression bonding. First measurements show sufficient output power and efficiencies.
Several types of grounded coplanar waveguides on thin dielectric membranes which have shown promising performance at lower frequencies (Dib et al, 1991) have been designed and characterized for D-band frequencies. Waveguides with different characteristic impedances have been fabricated and their S-parameters and propagation constants as well as their attenuation have been experimentally determined. Simulated and measured data are shown in this paper. Furthermore, low pass filters for D-band frequencies have been investigated. The classical five section approach (Robertson et al, 1996) has been optimized for a corner frequency of 120 GHz. Simulated and measured insertion and return loss are in close agreement. The investigated structures were measured using a test fixture which provides a transition from coplanar waveguide to conventional rectangular waveguide.
