A surface mountable microwave IC package includes a dielectric substrate; a ground conductor disposed on a front surface of a dielectric substrate on which a microwave IC chip is disposed and grounded; and a transmission line for connecting the microwave IC chip to a coplanar line on a package substrate outside the microwave IC package. The upper coplanar line is disposed on the front surface of the dielectric substrate and includes the ground conductor on which the IC chip is disposed. The lower coplanar line is disposed on the rear surface of the dielectric substrate. The intermediate coplanar line penetrates through the dielectric substrate and connects the upper coplanar line to the lower coplanar line. Therefore, the microwave transmission path from the package substrate to the IC chip is a coplanar transmission line so that a continuous transmission mode is maintained through the microwave transmission path. As a result, reflection of high frequency signals caused by the mismatching of characteristic impedances in the microwave transmission line is significantly reduced.

Microwave IC package

A module for encapsulating a microelectronic device has a polished mating surface around the periphery of the substrate on which is deposited at least one thin film sealband fabricated at a temperature no greater than about 400° C. The sealband has a thickness of less than about 0.001 in. and comprising a metal capable of wetting molten solder which has a melting point no greater than about 400° C. and adhering to the solder after solidification. A layer of the solder is disposed between the sealbands of the cap and substrate forming a hermetic seal for the module.

Hermetic thin film metallized sealband for SCM and MCM-D modules

An RF flexible printed wiring board transmission line for connecting strip transmission line microwave assemblies without the use of coaxial connectors and coaxial cables. The flexible transmission line includes a thin flexible dielectric ribbon, having on one side a ground plane layer and on the other side a microstrip conductor strip. Plated through holes at the ends of the flexible line provide access to both the ground plane and conductor strip on the same side of the flexible line, to facilitate interconnection of the microwave assemblies to the flexible line. The flexible line operates at microwave frequencies with little or no radiation leakage.

Microstrip flexible printed wiring board interconnect line

A ceramic substrate is provided with filled via holes for electrical or thermal feedthrough to or from an electronic device, each via hole having at least one dimension from about 4 to about 50 mils. The via holes are filled with copper, silver or gold for high conductivity and the filling is without visible voids at a magnification of 1000 diameters. The filling is preferably hermetic and is achieved by first electrodepositing metal into the holes and extending therefrom as dumbbell shaped plugs and then heating the substrate to the melting point of the metal so that metal from the dumbbell ends enters the connecting portion within the via hole to seal any aperture therein.

Ceramic substrates with highly conductive metal vias

Disclosed are components covered with a protective coating for use in a molten metal bath (or comparable environment) and devices including such components. The protective coating is preferably a ceramic sleeve adhered to a non-coated component by cement. A component with the protective coating is more resistant to degradation in molten metal than is the component without the coating, and may be manufactured by the process of (a) placing the protective coating over the non-coated component, and (b) injecting cement into the space between the non-coated component and protective coating, wherein at least some of the cement is injected through a passage in either the non-coated component or the protective coating.

Protective coatings for molten metal devices

An electronically reconfigurable digital pad attenuator is disclosed using selectively controlled segmented field effect transistors in a passive, non-gain state as the principal impedance elements. The attenuator may be fabricated in the monolithic microwave integrated circuit (MMIC) format with a segmented gate field effect transistor being connected in each of the separate branches of a Pi pad, Tee pad, or Bridged Tee pad attenuator configuration. The individual FET segments are maintained in a high admittance "ON" state or a low admittance "OFF" state in accordance with the binary control potentials applied to the gate of each segment, the principal electrodes being maintained at a zero potential difference. The attenuation then becomes a function of the binary gate potentials applied to each segment and assumes one of a set of well-defined discrete values. The attenuator consumes minimum power, provides attenuation steps that are independent of GaAs MMIC fabrication process tolerances, i.e. lot to lot stable, is wide band, is well matched at input and output terminals, and facilitates setting nominal gain in microwave and millimeter wave subsystems while minimizing transmission phase variations without degrading dynamic range, extending dynamic range in communications receivers, and wide band accuracy in vector modulators.

Electronically reconfigurable digital pad attenuator using segmented field effect transistors

The transition interconnects microstrip transmission lines whose finite-width conductors are formed on the upper surface and whose ground planes are formed on the under surface of a ceramic substrate. A patternable metallizable multilayer thick film dielectric is applied to the under surface of the ceramic substrate. The transition comprises first and second vias which penetrate the ceramic substrate inside and outside a hermetic enclosure. The upper ends of the vias are connected to the finite-width transmission line conductors, and the lower ends of the vias are interconnected by a finite-width conductor formed on the under surface of the substrate. The lower conductor then forms a transmission line of either a microstrip or coplanar nature with a ground plane available on the underside of the assembly. The thick film dielectric facilitates sealing, and attachment of a metal base plate. All steps are performed using thick film processing.

Hermetically sealed microstrip to microstrip transition for printed circuit fabrication

A digital phase bit is provided for microwave operation, comprising a pair of FET switches and at least three transmission lines. The FETs when operated in a digital switching mode, present a small impedance when on and a high impedance when off. Each of two of the transmission lines exhibits a series inductive impedance over the operating frequency band and shunts a FET switch, two shunt combinations being interconnected by the third transmission line. When the switches are on, the signal path is effectively through the FET switch alone (and not branched) and a reference phase shift is produced. When the FET switches are off, a signal applied to the phase bit branches at each shunt combination. The inductive reactance of the transmission line and the capacitive reactance of the FET switch of each shunt combination then jointly produce a resonantly enhanced reactance over the band, causing a reflection and a maximum differential phase shift. The reflections are cancelled at the input port by a suitable choice of length and impedance for the third transmission line. The phase bit is suitable for monolithic fabrication on a common semiconductor substrate and is bidirectional when symmetrical FET switches are used.

Digital phase bit for microwave operation

A bidirectional continuously variable phase shifting element is described for incorporation in a monolithic microwave integrated circuit (a circuit which combines both passive and active circuit elements). The preferred active device for use in the phase shifting element is a variable resistance field effect transistor (MESFET), while the preferred passive circuit element is a short transmission line interconnecting the principal electrodes. A variable phase shift for an RF signal passing through the phase shifting element is obtained by adjusting the gate potential of the MESFET between full conduction and nonconduction. The change in conductivity of the MESFET causes the serial impedance of the phase shifting element to vary from a substantially resistive impedance to a substantially capacitively reactive impedance arrangement, which requires only a single active device, is applicable to frequencies generally above 1 GHz, and provides phase shifts up to 45° with reasonable insertion loss and return loss.

John A. Windyka

Papers

Electronically reconfigurable digital pad attenuator using segmented field effect transistors

Hermetically sealed microstrip to microstrip transition for printed circuit fabrication

Digital phase bit for microwave operation

Continuously variable phase shifting element comprised of interdigitated electrode MESFET

Digitales phasenglied fuer mikrowellenbetrieb