Abstract: An analog voltage averaging circuit using active devices increases speed and resolution in analog to digital converters. The analog to digital converters combine the concepts of residue amplification and averaging to simplify the circuit implementation of high order, high speed analog to digital converters.

Abstract: A digital to analog converter employs an operational amplifier as an active summing device for summing a first analog voltage corresponding to most significant bits of a digital value and a second analog voltage corresponding to least significant bits of the digital value. In a multi-channel application, a single MSB DAC can be shared by all channels through first MUXs in each channel with each channel having an independent LSB DAC. Alternatively, a single LSB DAC can be shared by all channels through second MUXs in each channel. Gain of the voltage summing operational amplifier in each channel is determined by values of a resistor connecting the output of the LSB DAC to the inverting negative input of the operational amplifier and of a feedback resistor connecting the amplifier output to the inverting negative input.

Abstract: A digital to analog converter (DAC) incorporates a novel subranging voltage output DAC that delivers high multiplying bandwidth while consuming low power and requires small silicon area. The higher order digital input bits (MSBS) select a voltage range (VMSB) from a first resistor divider DAC network. The VMSB is then applied to the input of a small high speed low power differential input single ended output LSB programmable attenuator amplifier. Transistor follower devices effectively buffer the MSB section to the LSB section and increase bandwidth and speed of operation as well as permitting multichannel sharing of a single precision MSB voltage divider network.

Abstract: A method of interconnecting circuit components in a semiconductor integrated circuit including component elements formed in the substrate and thin-film resistors and capacitors formed on a surface of the substrate, a molybdenum plug is utilized to facilitate stable, uniform low resistance contacts to circuit elements, molybdenum (moly) plugs are utilized as a barrier between interconnect metallization and the circuit components. A CLAD moly/aluminum metallization interconnect can be fabricated in a standard process in which the moly plugs are formed. The accuracy and stability of thin-film resistors is facilitated during wafer processing, laser trimming, temperature cycling, and assembly processing thereby providing repeatable matching by eliminating contact resistance as a process variable.

Abstract: An integrated circuit structure for isolating circuit structures in closely packed integrated circuits, and a method for making the same. The isolation structure includes a semiconductor body having a surface, an insulatory layer on the surface having an aperture and an offset adjacent to the aperture, the aperture and offset being filled with epitaxial semiconductor material, at least a portion of the epitaxial material being single crystal semiconductor, said structure being used for the fabrication of standard semiconductor devices. The method uses conventional processing techniques that require a minimum of additional cost over prior art, and yet provide a high degree of device isolation and density.

Abstract: A semiconductor structure including a body of semiconductor material with selected surface areas of at least one surface of said body of semiconductor material including an oxide layer containing impurities characterizing a predetermined conductivity type, an inset region of said predetermined conductivity type under each of said areas formed by diffusion of impurities from said oxide layer and a silicon nitride layer covering said predetermined oxide areas and the remaining surface areas of said at least one surface of said body of semiconductor material.

Abstract: A multi-layer integrated semiconductor circuit interconnection structure with a first layer formed of a refractory metal sandwich including outer layers of silicon and a core of refractory metal providing a high temperature low ohmic contact assembly, an insulating layer formed on the first layer, and a patterned metal layer formed on the insulating layer to interconnect with the refractory layer and semiconductor device to provide an integrated circuit assembly.

Abstract: A radio which has assigned frequencies or channels for operation is prevented from operating on other channels. The frequency synthesizer in the radio is a large scale integrated circuit in a single semiconductor chip which is controlled by input codes from channel select switches. The synthesizer includes circuitry which responds to input codes for illegal channels and produces an inhibit signal thereby preventing generation of unauthorized frequencies. The circuitry may include a read only memory which is addressed by the input code. Alternatively, logic circuitry may be provided which responds to codes for illegal channels. Due to the circuitry being in integrated form, the method of inhibiting unauthorized signal generation cannot be easily circumvented.

Abstract: A multi-layer integrated semiconductor circuit interconnection structure with a first layer formed of a refractory metal sandwich including outer layers of silicon and a core of refractory metal providing a high temperature low ohmic contact assembly, an insulating layer formed on the first layer, and a patterned metal layer formed on the insulating layer to interconnect with the refractory layer and semiconductor device to provide an integrated circuit assembly.