Abstract: A system and method for orthogonal modulation of signals in communication systems. In the transmitter, differentially coded symbols are used to select time-shifted code sequences. The timing, or code position, of a code sequence is determined at the receiver by comparison to the previous code from the same channel, thus eliminating the need for dual-channel transmission and eliminating error due to differences in path propagation time. A fixed preamble code is also used to synchronize the receiver.

Abstract: High quality epitaxial layers of germanium can be grown overlying large silicon wafers by first growing an accommodating buffer layer on a silicon wafer. The accommodating buffer layer is a layer of monocrystalline oxide spaced apart from the silicon wafer by an amorphous interface layer of silicon oxide. The amorphous interface layer dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer. The accommodating buffer layer is lattice matched to both the underlying silicon wafer and the overlying monocrystalline germanium layer. Any lattice mismatch between the accommodating buffer layer and the underlying silicon substrate is taken care of by the amorphous interface layer.

Abstract: A composite semiconductor structure may be processed to form a compound semiconductor dynamic threshold-voltage field effect transistor. The compound semiconductor dynamic threshold-voltage field effect transistor may be provided by forming a compound semiconductor field effect transistor using a compound semiconductor region of the composite semiconductor structure and providing an electrical tie between a node at the gate of the transistor and a node at the body of the transistor. The node at the body may be a node that is coupled to a channel that is formed in the body when the transistor is conducting electricity. Dielectric isolation may be provided through an insulation layer that is in between the compound semiconductor region and non-compound semiconductor region of the composite semiconductor structure. Lateral isolation may be provided through trenches on the sides of the transistor that are filled with an insulator.

Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying a monocrystalline substrate of a semiconductor structure by forming a compliant substrate for growing the monocrystalline layers. An accommodating buffer layer comprises a layer of monocrystalline oxide spaced apart from a silicon wafer by an amorphous interface layer of silicon oxide. The amorphous interface layer dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer. An optical waveguide is formed in a monocrystalline layer grown on the semiconductor structure for distributing an optical signal to a selected portion of circuitry formed in the semiconductor structure. An optical source is formed in the semiconductor structure and coupled to the optical waveguide for generating the optical signal.

Abstract: A composite semiconductor including silicon and compound semiconductor, and having a metal semiconductor field effect transistor (MESFET) integrated at least partially with the silicon and at least partially with the GaAs having a silicon back gate is provided. The back gate for the MESFET may be formed by doping a region of the monocrystalline silicon substrate before forming the transistor. In a structure according the invention, integrated circuits may be provided to match the threshold voltages of one MESFET to another, improve the transconductance of a MESFET, and improve the switching speed of a MESFET.

Abstract: A process and a semiconductor structure are disclosed for fabricating substantially identical tuned ferro-electric components for varying the frequency or phase of a radio frequency signal at multiple locations of an integrated circuit using the same control voltage. The process includes the steps of epitaxially forming a monocrystalline layer of ferro-electric material on a monocrystalline ground plane; forming an input electrically coupled to the monocrystalline layer of ferro-electric material for receiving a bias voltage to vary at least one of a frequency and a phase of a radio frequency signal; epitaxially forming a monocrystalline layer of an electrically conductive material on the monocrystalline layer of ferro-electric material to constitute a transmission line; and forming an input electrically coupled to the transmission line for receiving the radio frequency signal.

Abstract: Apparatus and techniques for implementing wireless communication between integrated transmitters and integrated receivers are provided. By providing a semiconductor structure including silicon and a compound semiconductor, a single circuit can be integrated part in silicon and part in compound semiconductor. In a semiconductor structure according to the invention, a wireless transmitter and a wireless receiver can be integrated in a compound semiconductor portion of the structure and digital CMOS circuitry can be integrated in the silicon portion of the structure. This obtains substantially increased wireless transmission efficiency. The circuits according to the invention can be implemented with circuits that wirelessly transmit from one portion of the chip to another portion of the chip, or with circuits that wirelessly transmit from one integrated circuit to a second integrated circuit.

Abstract: A system and method for orthogonal modulation of signals in communication systems. In the transmitter, differentially coded symbols are used to select time-shifted code sequences. The timing, or code position, of a code sequence is determined at the receiver by comparison to the previous code from the same channel, thus eliminating the need for dual-channel transmission and eliminating error due to differences in path propagation time. A fixed preamble code is also used to synchronize the receiver.

Abstract: A process for merging and using the Mediation Device Protocol with a network layer protocol. Under the merged protocol, each device joining a network enters into two stages: the Set-Up Stage and the Normal Operational Stage. During the Set-Up Stage, the device identifies its neighbors, builds a neighborhood list, obtains a Logical ID, and picks a parent node in the network. After the Set-Up Stage is complete, the device enters the Normal Operational Stage where it will send/receive control and data messages, invite and help new nodes to join the network, recover from broken links or topology changes, and other normal network operations.

Abstract: A signaling system is provided in which a spread spectrum code is cyclically shifted by a cyclical shift dictated by a bit pattern of one or more bits. The cyclically shifted spread spectrum code is used to modulate a carrier frequency, and transmitted from a transmitter to a receiver. At the receiver the signal including the cyclically shifted spectrum code is demodulated to recover the cyclically shifted code. The cyclical shift is then determined and the bit pattern which is associated with the cyclical shift is output. The method can be used in direct sequence spread spectrum communication.

Abstract: A technique for intra-piconet location determination and tomography is described. This technique uses received signal strength indicator (RSSI) values in conjunction with transmitted power levels to determine the relative location of each device within a small network employing frequency hopped spread spectrum transmission. In addition to the location determination properties of the invention, the geometry of the devices in the network, as well as the path loss information between pairs of devices, may be used to infer the location of absorbers and reflectors within the piconet. This absorption and reflection information may be used in creating the piconet tomography. The approach described in this specification may be applied in conjunction with the Bluetooth wireless Personal Area Network (PAN) specification to determine device locations, mitigate the effects of multi-path, and perform indoor location and security functions, and other application functions requiring cost-effective location determination.

Abstract: A signaling system is provided in which a spread spectrum code is cyclically shifted by a cyclical shift dictated by a bit pattern of one or more bits. The cyclically shifted spread spectrum code is used to modulate a carrier frequency, and transmitted from a transmitter to a receiver. At the receiver the signal including the cyclically shifted spectrum code is demodulated to recover the cyclically shifted code. The cyclical shift is then determined and the bit pattern which is associated with the cyclical shift is output. The method can be used in direct sequence spread spectrum communication.

Abstract: A low power consumption protocol for low power communication devices attached to an asynchronous network is described. In this protocol, a communication device is used as a high communication duty cycle Mediation Device (MD), thus permitting other communication devices to use a low communication duty cycle framing structure. The MD functions as a storage and retrieval service for messages between two devices when one device is not able to communicate. When the previously unavailable device becomes available, it can check in with the MD to retrieve any missed messages and respond to these messages accordingly. In a communication network, each of the low power communication devices can be configured to behave as MD's for a small amount of time. Sharing this responsibility among all communication devices in the network allows each device to maintain an low average communication duty cycle. This technique is applicable to a low power, low cost, zero-configuring, self-organizing, asynchronous network.

Abstract: A method for determining whether a baud rate of a frequency modulated (FM) signal received by a receiver matches a predetermined baud rate. A parameter other than the baud rate is detected and used to confirm whether baud rate detection should be made, or whether if made, is reliable. The parameter is frequency deviation of the received FM signal, or other suitable parameters of the received FM signal.

Abstract: A zero-intermediate frequency receiver circuit (11) for receiving a radio frequency signal detected by an antenna (14). The receiver circuit (10) comprises a second local oscillator circuit (25) and an oscillator circuit (60) of a phase locked loop demodulator (36) which are identical and track each other so as to provide a more accurate reference for processing a demodulated signal. A current reference (39) providing a current reference signal utilized by the second local oscillator circuit (25) and the oscillator circuit (60) of the phase locked loop demodulator (36).

Abstract: A phase locked loop (PLL) circuit for use as a demodulator and other applications. The PLL circuit (200) comprises a phase detector (210), a transconductance amplifier (212) and a current controlled oscillator (ICO) (214). The phase detector has two signal inputs and two outputs, and detects a phase difference between signals at its inputs. A capacitor C1 is connected to the output of phase detector (210) and develops an output voltage signal vo(t). A transconductance amplifier (212) is coupled to the capacitor C1 and converts the output voltage signal vo(t) to an output current signal. The ICO (214) is coupled to the transconductance amplifier (212) and the second output of the phase detector (210) and generates an output signal having a frequency which is proportional to an input current signal. The output signal of the ICO (214) is coupled to the second signal input of the phase detector (212).

Abstract: A peak and valley measuring circuit (40) featuring a single digital-to-analog converter (DAC) (100), a peak counter (110), a valley counter (120), and a comparator (130). The peak and valley measuring circuit (40) uses the peak counter (110) when detecting peaks of the recovered audio signal and the valley counter (120) when detecting valleys of the recovered audio signal. The DAC (100) is used in conjunction with one of the counters (110) or (120) depending on whether peaks or valleys are being detected, and is preferably a current-mode DAC.

Abstract: A paging system includes a plurality of paging receivers (14, 16), each paging receiver having a display (19) for presenting the at least a portion of a representation of graphic information which substantially resembles at least a portion of graphic information received from a facsimile unit (11). The paging system further includes a paging terminal (13) capable of receiving graphic information received from the facsimile unit (11) and transmitting the representation of graphic information to the paging receiver (16).

Abstract: A high stability oscillator circuit 100 having an output 150 and a multiple of reference oscillators 102, 104, and 106 for enhanced stability and reliability is disclosed. The output signals of these oscillators 108, 110, and 112 are mixed and analyzed for determination of excessive frequency shift including component failure. Additionally a switch 148 decouples the shifted oscillator signal from the output of the circuit 150 and couples another one of the oscillators in its place.