Abstract: An improved apparatus for implementing shell mapping in a PCM modem incorporates u-law signal mapping points. An improved signal point encoding technique effectively employs ring-indices that are generated in accordance with known principles. The ring indices are applied to a reordering module, which rearranges the ring indices produced by a conventional shell mapping algorithm. A preferred reordering scheme takes advantage of the non-uniform probability distribution provided by the conventional shell-mapping algorithm. The rings are rearranged such that the sets of signal points having relatively small separation distances are assigned to rings with relatively low frequencies of occurrence, while the sets of signal points having relatively large separation distances are assigned to rings with relatively high frequencies of occurrence. The reordering scheme optimizes the signal point assignment while maintaining acceptable limits for average transmission power.

Abstract: An apparatus and method for power management of embedded electronic subsystems. A power management control circuit for managing power to an embedded subsystem includes a subsystem power node connected to a first section of the embedded electronic subsystem and a bias voltage node connected to a second section of the embedded electronic subsystem. A power switch is connected between a power supply and the subsystem power node. By separating the power subsystem node from the bias voltage node, power can be removed from the subsystem, while still providing the necessary bias voltage to the electronic static discharge (ESD) diodes. This prevents the voltages applied to the system bus by the subsystem from causing bus contention or system bus lock-ups. A power removal and restoration procedure is also disclosed.

Abstract: A frequency acquisition and compensation device and method for direct sequence spread spectrum communications systems has an identification (ID) sequence in an acquisition frame which is received by a receiving station and an ID sequence stored in an ID register. A received acquisition frame is demodulated using dot product and cross product demodulation. An ID detector detects the ID sequence in the demodulated dot product, cross product, or inverse cross product acquisition frame. When the ID is detected by the dot product demodulator, the receive frame timing is adjusted to coincide with a time interval when the ID was detected. Also, when the ID sequence stored in the ID register matches either the dot product, cross product or inverted cross product of the received ID sequence, the system microcontroller updates the automatic frequency control value.

Abstract: An image processing system uses probability error diffusion, and is implemented using a variety of devices capable of reproducing image data including color photo-copy machines, color facsimiles, color printers, black and white printers, and digital printers. The image processing system is employed in a multi-functional peripheral capable of performing several functions. The image processing system identifies which channels in a printing device will print a pixel, and applies error diffusion to those channels. The image processing system determines characteristics of the pixel and subsequently calculates a pixel placement probability, and then applies the error diffusion to the pixel placement probability. Error diffusion may also be applied to a difference between the pixel placement probability and a print probability.

Abstract: A speaker-dependent (SD) speech recognition system. The invention is specifically tailored to operate with very little training data, and also within hardware constraints such as limited memory and processing resources. A garbage model and a vocabulary model are generated and are subsequently used to perform comparison to a speech signal to decide if the speech signal is a specific vocabulary word. A word score is generated, and it is compared to a number of parameters, including an absolute threshold and another word score. Off-line training of the system is performed, in one embodiment, using compressed training tokens. A speech signal is segmented into scramble frames wherein the scramble frames have certain characteristics. For example, length is one characteristic of the scramble frames, each scramble frame having a length of an average vowel sound, or a predetermined length of nominally 40-50 msec. The invention is operable to be trained using as little as one single training token that is segmented.

Abstract: The present invention discloses an improved system and method for increasing the timing accuracy of a time domain multiple access (TDMA) mobile communication system using a resource efficient parabolic interpolator. With the present invention, a mobile unit receives burst transmissions from a base station and a timing information is recovered therefrom. Since the timing information establishes the time of arrival of the burst, correlation initially identifies a coarse approximation of the location of the control signal within a defined portion of the burst signal and, together with two adjacent samples. Using a curve fitting technique, a precise position of the peak, relative to the coarse position, is determined. The equation can be solved ahead of time and values from the three samples substituted into a single expression for evaluation. Once the coefficients of the equation are known, the time offset of a refined peak relative to the coarse peak is readily calculated.

Abstract: A circuit for implementing a first order noise shaping apparatus for use in data converters employing thermometer-code based elements is disclosed. Raw thermometer code is rotated by up to four columns of shifters such that the code is rotated up to 15 positions. In this manner, the elements of the data converter may equally participate in the conversion process, thereby minimizing the effects of mismatched elements in a data converter by distributing errors due to mismatched elements. Such a process may be used in digital to analog converters and analog to digital converters such that a suitable data weighted algorithm can be used.

Abstract: The present invention relates to a portable folding communication device comprising a top portion, a bottom portion, and a cylindrical hinge connecting the top and bottom portions. The cylindrical hinge houses an integrated battery compartment. In a preferred embodiment, the device uses a rechargeable AA lithium ion cell, which can be inserted from one end of the cylindrical hinge.

Abstract: In a phase lock loop, a charge pump includes a current mirror circuit. The current mirror circuit contains a bias current source and a current mirror source which mirrors the current of the bias current source. The current mirror source is turned on and off in accordance with an output signal from a phase detector to produce correction signals for a VCO. To conserve power, circuits are provided for turning the bias current source on just before it is needed by the current mirror source and for turning the bias current source off just after the current mirror source turns off.

Abstract: A system having dualband power amplifier control in a dualband phone is provided using a single power amplifier controller. The dualband phone includes two power amplifiers, where each power amplifier amplifies the power of a signal transmitted at a different frequency band. A power amplifier controller is provided for controlling the amount of amplification performed by both of the power amplifiers, and a power amplifier switching device is connected to the power amplifier controller for switching the connection of the power amplifier controller between the two power amplifiers. The system further includes a processing device which monitors the quality and strength of the received signal transmitted by various base stations in the transmission region of the dualband phone.

Abstract: The present invention improves the stability and enhances the gain of amplifiers, particularly transistor amplifiers, by using mutual inductive coupling to partially cancel feedback current. Inductors at the input and output of an amplifier are positioned so that a mutual inductance is created between the two inductors. The mutual inductance is used to cancel the inherent capacitive feedback of transistor amplifiers. The use of mutually coupled inductors allows a large value of effective inductance to be obtained by using relatively small inductors. The use of mutually coupled inductors also avoids the problem of low-frequency instability.

Abstract: A modem system includes a programmable synchronization signal format that can be configured at a first modem in response to a request received from a second modem. The synchronization signal format may define a number of parameters of the synchronization signal, such as the sign pattern for symbols transmitted by the first modem during a training sequence. The specific parameters of the synchronization signal format may be associated with the design and operation of the second modem. For example, the particular timing recovery and automatic gain control schemes used by the receiver portion of the second modem may be optimally initialized with a synchronization signal having a specific length, amplitude, or spectrum.

Abstract: A phase-locked loop includes a phase/frequency detector, a charge pump, a loop filter, an oscillator and a feedback circuit coupled between the oscillator and the phase/frequency detector. The loop filter includes a first temperature-variable well resistor and has a gain directly related to resistance of the first resistor. An oscillator coupled to the loop filter includes a voltage-to-current converter that generates a reference current based on the loop filter voltage, and a current-controlled oscillator that generates the output clock based on the value of the reference current. The voltage-to-current converter includes a first transistor that receives the loop filter voltage at a gate and a second temperature-variable well resistor coupled to the source of the first transistor. The oscillator gain is indirectly related to the resistance of the second resistor. The second well resistor and first well resistor have substantially equal resistances and substantially equal temperature coefficients.

Abstract: A digital subscriber line (DSL) communication system that utilizes the high frequency band of a standard telephone line does not require the use of a plain old telephone service (POTS) splitter in the resident's home, which provided isolation between the POTS frequency band (0 to 4 kHz) and the DSL frequency band. Digital signal processing techniques are utilized to adapt to varying subscriber line conditions due to POTS telephone equipment. The digital signal processing techniques eliminate the need for a splitter by reducing susceptibility to distortion due to varying subscriber line characteristics. The digital subscriber line modem utilizes constant envelope modulated signals and frequency division multiplexing, where the constant envelope modulations lessens the intermodulation distortion products due to DSL signals that are transmitted by the modem and which may result in audible noise at the POTS telephone equipment due to non-linearities of the POTS telephone equipment.

Abstract: An interconnect structure and fabrication method are provided to form air gaps between interconnect lines and between interconnect layers. A conductive material is deposited and patterned to form a first level of interconnect lines. A first dielectric layer is deposited over the first level of interconnect lines. One or more air gaps are formed in the first dielectric layer to reduce inter-layer capacitance, intra-layer capacitance or both inter-layer and intra-layer capacitance. At least one support pillar remains in the first dielectric layer to promote mechanical strength and thermal conductivity. A sealing layer is deposited over the first insulative layer to seal the air gaps. Via holes are patterned and etched through the sealing layer and the first dielectric layer. A conductive material is deposited to fill the via holes and form conductive plugs therein. Thereafter, a conductive material is deposited and patterned to form a second level of interconnect lines.

Abstract: A gated-delay locked loop that generates an output clock in phase with and having a frequency which is an integer multiple of the frequency of a reference clock. The gated delay-locked loop includes a voltage-controlled gated oscillator having first and second serially connected voltage-controlled delay elements that each introduce a time delay to produce a first delayed clock and the output clock. An S-R flip-flop receives the first delayed clock on its R-input and either the output clock or the reference clock on its S-input to produce a loop clock. The loop clock is provided to the first delay element. A multiplexer selects the reference clock as the S input to the flip-flop once every N cycles, and selects the output clock as the S input the remaining N−1 cycles. A phase detector, a charge pump and a loop filter compare the phase of the output clock to the phase of the reference clock and apply a voltage to the delay elements to correct any phase differences.

Abstract: A communication system capable of communicating RF signals at any one of a plurality of communication standards through a common antenna is disclosed. The communication system includes a transmitting unit having at least one transmit RF information signal output, and a receiving unit having at least one receive RF information signal input and a GPS RF information signal input. The transmitting unit includes a modulator for modulating a transmit IF with a transmit baseband information signal to generate a transmit IF information signal and an upconverter for upconverting the transmit IF information signal with a transmit RF to generate at least one transmit RF information signal.

Abstract: A dual band RF architecture including a GSM quadrature modulator for modulating an intermediate frequency (IF) wherein the frequency of the modulated IF signal is changed such that one IF is used for the GSM band and another IF is used for the DCS 1800 band. An intermediate frequency (IF) filter with a pass band that covers both the GSM IF and the DCS 1800 IF is connected to the output of the modulator and outputs to a transmit phase lock loop, which translates the IF signal from the IF filter to either a DCS 1800 band radio frequency signal or a GSM band radio frequency signal, depending on the frequency of a local oscillator (LO). The receiver employs a down converter which provides a down converted output signal selected by high side injection for the GSM band an by low side injection for the DCS 1800 band.

Abstract: A method and apparatus are disclosed for using formic acid vapor as a reducing agent during wirebonding operations to a semiconductor chip. The method and apparatus are particularly useful when wirebonding to copper metal pads. While maintaining a preferred reaction temperature between 190° C. and 210° C., a copper metal pad is exposed to formic acid vapor during wirebonding to remove copper oxidation from the pad to permit a good wirebond to be achieved. A less preferred reaction temperature range is 150° C. to 360° C. In accordance with another aspect of the invention, the concentration of formic acid vapor is controlled by mixing formic acid vapor with a gas such as nitrogen that does not participate in the reduction chemical reactions. Reaction by-products, such as carbon monoxide and hydrogen gas, may be recirculated back to further participate in the reduction chemical reactions.

Abstract: A method of coding speech under background noise conditions or during noise-like speech periods wherein during active voice speech segments an analysis-by-synthesis method is used. However, when a background noise segment or noise-like speech segment is detected, an adaptive code book (pitch prediction) contribution is used as a source of a pseudo-random sequence in order to provide a better representation of the background noise or the noise-like speech. An improved gain quantization scheme is also employed when a background noise segment is detected, wherein energy of the total excitation with quantized gains is matched to the energy of total excitation with unquantized gains.