Abstract: A circuit and method for sensing in current mode when a telephone has been answered in a telephone system in which an answer is indicated when a dc component of a signal across a resistor exceeds a predetermined reference current. Currents sensed at the terminals of the resistor are combined to provide a third current that includes the dc component, without attenuation of the dc component. A filter separates the dc component from the third current so that the dc component can be compared to the reference current.

Abstract: A high voltage protection circuit includes breakdown networks for providing a discharge path between a pair of terminals of a circuit to be protected. Each network conducts current between a supply terminal and another terminal at a low threshold voltage value when power is removed from the supply terminal. The network increases the threshold value when power is applied to the supply terminal to prevent conduction through the breakdown network during normal operation of the circuit to be protected. In one implementation, the protection circuit includes anti-latching circuitry connected to the breakdown network for preventing the breakdown network from latching on after or during the time power is applied to the supply terminals. To minimize the degradation of DC operating characteristics, the leakage currents, due to the protection circuit, between the first terminal and the positive supply terminal, and between the first terminal and the negative supply terminal cancel each other.

Abstract: A circuit and method for stabilizing a common mode voltage in a differential circuit provides a desired common mode voltage V.sub.cm to control terminals of two transistors which provide the variable resistance for setting the common mode voltage. V.sub.cm is sampled between load resistors R.sub.L connecting operating terminals of the two transistors and applied directly to their control terminals. A known common mode current I.sub.cm is accepted by each transistor, leaving a differential current I.sub.d to flow through load resistors R.sub.L. The circuit and method find application in a variety of uses, including transconductance and transresistance amplifiers and automatic gain control circuits.

Abstract: A fabrication process for dielectrically isolated high frequency complementary analog bipolar and CMOS transistors. Polysilicon extrinsic bases, polysilicon emitters with sidewall spacers formed after intrinsic base formation provides high current gain, large emitter-to-base breakdown voltage, large Early voltage, and high cutoff frequency.

Abstract: A transceiver and method of tuning a transceiver having a remote unit and a local unit. The remote unit includes a modulation section having a transmit frequency synthesizer and a receive frequency synthesizer and a frequency conversion section having a fixed frequency local oscillator, a transmit mixer and a receive mixer. The transceiver may be tuned by remotely controlling the synthesizers to select the frequency and/or data to be transmitted and the frequency and/or data to be received.

Abstract: In a semiconductor island structure with passive side isolation, a method and structure for reducing corner breakdown where a device conductor crosses the edge of the island. The decrease in the field strength at the island edge between the conductor and the adjacent conducting region may be achieved by increasing the depth of the insulator beneath the conductor where it crosses the island edge without the necessity for increasing the thickness of the layer of insulation applied directly to the surface of the island by the use of a second or higher level interconnect, e.g., the conventional deposition of one or more additional layers of insulation over the device terminal to increase the spacing between the conductor and the surface of the island. In this way the process by which the device is constructed may remain unchanged.

Abstract: A locking-unlocking mechanism is disclosed which is capable of realizing firm and reliable connection between pipes when a plurality of pipes telescopically arranged are extended, and capable of disconnecting the connected pipes rapidly and precisely.

Abstract: A method and device for timing bit transitions in a data communication system includes a multi-purpose counter/decoder responsive to transmission of bit transitions and receipt of reflections of the transmitted bit transitions to (a) indicate when the next bit transition is to be transmitted after a bit transition has been received during normal operation, (b) indicate a fault when a reflection of the transmitted bit transition is not received within a predetermined time count, and (c) determining the duration of a received bit.

Abstract: An antenna and method of minimizing capacitive effects of a capacitive body on a loop antenna. The antenna includes a loop antenna, a drive circuit for driving a current through the loop antenna, matching means for matching the impedance of the drive circuit and the loop antenna and a housing for carrying the loop antenna, drive circuit and matching means. The loop antenna is formed from a band of conductive material such that the flat sides of the band are normal to the plane of the loop. The loop antenna is carried by the housing when the housing is carried by a human body with its flat sides normal to the human body and its edges parallel to the human body. The orientation of the loop antenna relative to the human body minimizes the capacitive effect of the human body on the loop antenna and thus decreases the impedance to the flow of current through the loop antenna.

Abstract: A loop filter for a phase locked loop (PLL) circuit may include two operational amplifiers and switched-capacitors connecting the inverted input and output of the operational amplifiers, the switched-capacitors replacing resistors found in conventional loop filters for PLL circuits. The loop filter may be in a monolithic integrated circuit, and the PLL circuit may operate with a response time heretofore available only with individual (non-IC) components. Phase error due to amplifier offset may be reduced with offset nulling techniques.

Abstract: A method and circuit for loopback testing a telephone subscriber line interface circuit (SLIC) includes current sources connected to each of tip and ring circuits from which switch-hook is detected in the SLIC. A loopback test of the SLIC is conducted when the telephone is on-hook and is successful when the current from the current sources simulates a switch-hook detection, The current sources may also be used during on-hook transmission. A ground key detect circuit in the SLIC may be used to verify a successful loopback test by using current from the current sources in the ground key detect circuit to check for a grounded ring circuit in the SLIC.

Abstract: A multiple output filter coupler for providing plural RF output signals from a single RF input signal may include an RF waveguide filter for receiving an RF input signal at one end thereof and for filtering the received RF input signal along its length, and plural connectors attached to the waveguide filter's end cavity for providing plural filtered RF output signals. Tuners attached to the waveguide filter proximate the connectors may be used to vary the relative signal strengths of the filtered RF output signals. The filter coupler's output and input may be interchanged to provide a single output from multiple inputs.

Abstract: A integrated circuit, high impedance, current source/sink for wireless communications systems comprising one or more inverted bipolar junction transistors, and a method of ensuring high output impedance at RF frequencies. Mixers, differential amplifiers and transconductance amplifiers are disclosed as is the physical structure of bipolar transistors including heterojunction transistors.

Abstract: In a direct sequence spread spectrum receiver, an apparatus for obtaining and adjusting bit synchronization. In one aspect, the bit synchronization is adjusted by selectively inverting a clocking circuit to delay sampling by one-half a clock cycle and to combine the inversion with a skipping of one cycle to advance the sampling by one-half cycle. In another aspect of the invention, the synchronization circuit avoids overflow of accumulating components by downshifting both the partial sums and the input data when needed.

Abstract: A method of processing wafers for power devices in which the wafer has a desired thickness less than the thickness necessary to provide mechanical support. A silicon wafer of the desired thickness is bonded to a carrier wafer until most, if not all, of the processing steps are completed, after which the silicon wafer is separated from its carrier wafer. The carrier wafer may serve as a diffusion source, and the areas of the bonding of the silicon wafer to the carrier wafer may be selected consistent with the devices or groups of devices to be formed by the separation of the two wafers. The carrier wafer may by bonded to the device wafer over nearly the full surface area and the carrier wafer remain a part of the final device.

Abstract: A semiconductor device may include complementary NPN and PNP transistors and a JFET that is formed in the same steps as used to form the transistors. The bottom gate of the JFET and the back collector layer of the PNP transistor are doped and up-diffused in the same steps to cause the channel of the JFET and distance between the base and back collector layer of the PNP transistor to be the same. The JFET may have a low voltage capability (less than 5 volt pinch-off voltage) and the PNP transistor may have a breakdown voltage of at least 30 volts.

Abstract: A membrane apparatus includes a bubble supplying portion for supplying micro bubbles which is provided at a location in the vicinity of the entrance of a flow passage for raw liquid. Thus, the growth of a gel layer on a membrane surface can be prevented, and a large filtering amount can be maintained while preventing sludge from blocking the membrane. Moreover, since bubbles uniformly pass through the inter-membrane passages, sludge blocking can be evenly prevented over the entire surface of the membrane. When a flat membrane is used as the filtering membrane, there is provided an advantage of reducing the frequency of work for disassembling the frame and cleaning the membranes. A membrane treatment apparatus includes the membrane apparatus, an aeration apparatus, a circulating tank, and a filtrate pump.

Abstract: A system and method of remotely recording a telephone message at a selected recording device connected to a telephone receiver by an RF link may include a base station having an RF transmitter connected to a telephone receiver, and plural paging/recording devices, each with an RF receiver and a message recorder. The paging/recording devices may be contained within suitable children's toys. A caller calls the telephone receiver and when the telephone connection has been made provides a first code signal to the telephone receiver to gain access to the RF transmitter, and then provides a second code signal to identify a particular paging/recording device that is to receive and record the message.

Abstract: A method of making a semiconductor device in which a polysilicon gate is separated from a semiconductor substrate by a re-oxidized nitrided oxide film and in which the concentration of re-oxidized nitride in the film underlying the gate is non-uniform. The concentration of nitrogen in the substrate and the re-oxidized nitrided oxide along their interface and underlying the gate is non-uniform. The non-uniform concentrations are provided by incomplete shielding of the oxide by the gate during the nitriding and re-oxidizing processes.

Abstract: Integrated circuit memory with bitlines which cross each other in multiple place for symmetric capacitives coupling. Also read only memory with differential sense amplifier with an input to each half array of cells. Bits are stored complementarily in the two halves.