Abstract: A power amplifier comprises an input stage having a fully differential amplifier with differential inputs and differential outputs, and a high impedance closed loop common mode feedback control circuit deriving common mode feedback control signals from the differential outputs. The output stage of each differential output of the input stage comprises a class AB amplifier having source followers interfacing with the fully differential amplifier. A common mode output voltage control circuit maintains the common mode output voltage of the class AB amplifiers at a desired level. A quiescent current regulator comprises a circuit for mimicking the behavior of one of the source followers to derive a control signal for maintaining the quiescent current of the output transistors at a desired value.

Abstract: A telecommunications system with a call waiting feature, comprises a central office and a plurality of subscribers. The system includes an arrangement for transmitting a signal over an off-hook line to alert the subscriber to the presence of an incoming call, and a cancel call waiting (CCW) register at the central office. The CCW register is associated with each subscriber line and is set to cancel the call waiting feature in response to receipt of a cancellation code over the associated subscriber line and is reset upon termination of a subsequent call. The central office further comprises a delayed cancel call waiting (DCCW) register for each subscriber line with at least a first state and a second state. The DCCW register is set to the first state in response to receipt of a DCCW access code transmitted over its associated subscriber line. An arrangement is provided for checking and resetting the state of said DCCW register when the associated line goes off hook in response to an incoming call.

Abstract: A mobile wireless communications system, comprises a plurality of base stations with associated respective coverage zones, each base station being connected to a central host computer and being capable of establishing two-way communication with mobile units in its associated coverage zone and a switch having a plurality of line interfaces connected to the base station. The host computer can select one of the base stations in range of an active mobile unit to establish a call therewith, determine the line interface associated with the call, determine when a hand off from one base station to the next is to occur as the active mobile unit moves between coverage zones, send a hand off message to the switch identifying the current active line interface and the target line interface after hand off associated with the call, and initiate a hand off by sending a call originate message to the next base station instructing it to originate the call on the target line interface.

Abstract: A class message receiver that in one embodiment can be implemented in a Digital Signal Processor. An FSK demodulator takes input linear samples of the signal and filters them with a bandpass filter which does an upsampling to increase the sampling rate from 8,000 Hz to 24,000 Hz, which results in 20 samples at the output of the bandpass filter for each incoming data bit. The amplitude of the signal/samples at the output of the bandpass filter is adjusted by an automatic gain control (AGC) circuit and the resulting samples (for convenience referred as sample (t), where t is a discrete moment in time) are processed along two different paths designed to estimate the likelihood of the input signal encoding a mark (mark estimation path) or a space (space estimation path).

Abstract: A method of defining the operation of switching system peripherals is comprised of storing a software program for operating the peripherals in a switching system; storing at least one table of data for access by the program for defining operating parameters of a corresponding at least one peripheral; modelling a prototype of the peripheral in a remote host system by creating a human-machine-interface simulating the peripheral; storing a control table of data corresponding to the modelled prototype in a memory for the host system; and downloading the control table into the one table, whereby operation of the peripheral is controlled by the operating software programs and the data in the at least one table.

Abstract: A method of translating a command into natural language is comprised of the steps of: storing compressed words of the language once as either a word or subset of a word or group of adjoining words in a memory; storing a numeric indicator of each group of tokens which form a natural language string, with position locators; looking up the position locators in response to the command; accessing the memory to retrieve the compressed words; and providing a string of the tokens as a natural language string.

Abstract: A method of planarizing a semiconductor wafer having interconnect tracks of formed thereon, comprises applying a layer of inorganic spin-on glass to the wafer, curing the spin-on glass at a temperature not exceeding about 450.degree. C., then placing the wafer in a dielectric deposition chamber, subjecting the wafer to in situ disconnection and outgassing of water and reaction by-products, and then capping the wafer in a moisture-free environment with a protective dielectric layer resistant to moisture diffusion.

Abstract: A wireless communication system comprising a plurality of antennae, the antennae being arranged in a grid pattern over a communication region, wireless portable terminals located within the communication region for emitting and/or receiving electromagnetic signals via the antennae, apparatus for determining the position of at least one of the terminals within the communication region relative to the grid pattern.

Abstract: A semiconductor test chip for use in semiconductor fabrication fault analysis, comprises an n.times.m array of transmission gate cells arranged such that within a given row respective strips of conductive material of a first type form common source and drain electrodes for the transistors of the row, the sources and drains of each row being independent, and within a column strips of conductive material of a second type form common gate electrodes such that each column of transistors can be turned on independently. An input circuit permits a predetermined bit pattern to be selectively applied to the inputs of the rows of transmission gate cells. A demultiplexer including output transmission gates is connected to respective outputs of the rows of the array for selectively addressing the output of each row of transmission gate cells.

Abstract: A method of applying a spin-on glass layer to a substrate is disclosed characterized in that the spin-on glass is applied as a plurality of contiguous thin layers that together form a composite layer. Each thin layer is cured prior to the application of the next layer at a temperature of at least about 300.degree. C., preferably 350.degree. C., for a time sufficient to permit catalyst connection and substantially eliminate volatile residual solvents contained therein. In this way cracking in organic SOGs can be substantially eliminated, and beneficial results can also be achieved with quasi-organic SOGs.

Abstract: A keypad is comprised of a supporting frame, a plurality of snap action domes, and a plurality of pushbuttons each overlying a dome, all of the above being integrated and formed of a single piece of elastomeric material, the pushbuttons each being surrounded by a thin piece of the material buttressing the pushbutton upwardly, each of the thin pieces of material and an associated portion of the pushbutton forming a dome. The thin pieces of material extend from and are continuous with the frame. Each conducting button is disposed below a corresponding dome and is located such that when a pushbutton is pushed downwardly, its associated dome collapses, moving an associated button downwardly.

Abstract: A high speed communication link between peripheral nodes and a single multi-link layer protocol (MLAP) controller with an integrated HDLC framer in a main control complex. Peripheral nodes contain a very simple control that forwards all the HDLC D-channel data from the peripherals to a single MLAP controller, thus making the peripheral nodes small in physical size, extremely flexible to connect to new interfaces and very portable. Accordingly it facilitates the efficient distributed deployment of the PABX. Using the described system, the PABX itself may be distributed around a building, using a backbone high speed link. Peripheral nodes may be located at various places in a building with peripherals such as line interfaces and associated digital telephones at locations as needed. They need not be centralized, adjacent the main control complex, as is now required. This facilitates the provision of a building with a flexible communication system having substantially reduced wiring requirements.

Abstract: A method of producing insulating layers over a semiconductor substrate comprising spinning a film of spin-on-glass (SOG) over a semiconductor substrate, precuring the film of SOG at an elevated temperature sufficient to remove the bulk of solvent and curing the film of SOG in a plasma in a plasma reactor of a type exhibiting a self-biased R.sub.F discharge adjacent the SOG for a period of time sufficient to exclude the bulk of SiOH, organic volatiles and H.sub.2 O from the layer.

Abstract: A special host routing code is transmitted from the remote switch to a host switch which advises the host switch whether the call is to be made to a subscriber local to the host switch or to a remote subscriber via an external telephone system trunk connected to the host switch. In the set up of a call, two steps are executed in addition to those of a normal switch-to-switch communication which functions to set up a path from the remote switch through, or to the host switch. These steps are the outpulsing of a host routing code from the remote switch over a specified trunk to the host switch and waiting for an acknowledgement, such as a wink (temporary line open or close condition). This causes the host switch to set up a cut-through path through the host switch, allowing the remote switch to tandem through the host switch. The digits dialed by subscribers on both switches to affect similar types of calls are therefore similar, and similar types of switches can be used for the remote and host switches.