Abstract: Method and circuitry for implementing an inductor-capacitor voltage-controlled oscillator with improved overall performance. In an exemplary embodiment, the present invention includes two phase shifters and an interpolator. The two phase shifters are coupled to the interpolator in a loop configuration. That is, output from the two phase shifters are fed into the interpolator. The output of the interpolator, in turn, is fed back to the two phase shifters. The two phase shifters and the interpolator respectively utilize LC tanks having different fixed resonant frequencies, with the first phase shifter resonant frequency being the lowest, the interpolator resonant frequency being in the middle and the second phase shifter resonant frequency being the highest. Signals from the first and second phase shifters are selectively combined by the interpolator according to a control signal. Thus, the VCO can be continuously tuned near the resonant frequency of the interpolator.

Abstract: The present invention provides an overflow detector for a FIFO. The FIFO includes a plurality of registers each having an input and an output, a plurality of write signals each respectively coupled to a clock, one of the plurality of registers, and a plurality of read switches each respectively coupled to an output of one of the plurality of registers, each of the plurality of read switches being controlled by a respective read signal. The overflow detector includes a plurality of clocked registers each of which is coupled to receive a write signal and its corresponding read signal, wherein each clocked register records a read signal and is clocked by the corresponding write signal.

Abstract: A cable modem system and method is provided for the transfer and processing of data in accordance with specialized data transfer protocols while utilizing conventional cable modem termination system (CMTS) equipment. A cable modem system in accordance with the invention includes a cable modem that provides for the modification of data packets in accordance with one or more proprietary protocols and the addressing of the modified data packets to a CMTS. The CMTS is adapted to reconstruct the data packets.

Abstract: A line driver selectively drives one of two transmission lines. The line driver includes a differential amplifier connected to first and second differential switches. The first differential switch is connected between an output of the differential amplifier and a first of two transmission lines. The second differential switch is connected to the output of the differential amplifier and to the second of two transmission lines. The first and second differential switches are controlled by respective first and second control signals. The output of the differential amplifier is connected to either the first or the second transmission line in response to the first and second control signals. The differential switches include loopback protection to an prevent an incoming signal from passing from one transmission line to another during power down mode.

Abstract: A method of handling data packets in a series of network switches is disclosed. An incoming data packet is received at a data port of a first switch of the series of network switches and a stack tag is resolved from a header of said incoming data packet. It is then determinined whether an incoming data packet is a unicast packet, a multicast packet or an IP multicast packet; and the address resolution lookup and layer three IP lookup tables are searched to find an egress port for said incoming data packet. The packet header is modified and the packet is forwarded to at least a second switch of the series of network switches, on a stacked connection operating at a first data rate, based on the stack tag and the egress port. The header is later remodified when the egress port is one of a series of data ports of a particular switch of the series of switches.

Abstract: Methods and systems for applying digital dither includes methods and systems for applying digital dither in data converters, such as, for example, delta-sigma data converters. In an embodiment, an analog signal from a first path of a delta-sigma modulator is quantized to an m-bit digital signal and an n-bit dithered digital feedback signal is generated from at least a portion of the m-bit digital signal. The n-bit dithered digital feedback signal is converted to an analog feedback signal and fed back to a second path of the delta-sigma modulator. In an embodiment, the n-bit dithered digital feedback signal is generated by selecting one of a plurality of sets of n-bits from the m-bit digital signal depending upon a state of a dither control signal. The dither control signal can alternate between a plurality of states or pseudo-randomly switch between a plurality of states.

Abstract: A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode.

Abstract: Methods and systems for improved feedback processing in delta-sigma modulators, including single bit and multi-bit delta-sigma modulators, continuous-time and discrete-time delta-sigma modulators, and digital and/or analog feedback loops. One or more processes are performed in a pipeline having a higher throughput rate than a throughput rate of a delta-sigma modulator. Any of a variety of processes and combinations of processes can be performed in the pipeline including, without limitation, quantization, digital signal processing, and/or feedback digital-to-analog conversion.

Abstract: A network switch for network communications includes a first data port interface supporting a plurality of data ports transmitting and receiving data at a first data rate. A second data port interface supports a plurality of data ports transmitting and receiving data at a second data rate. A CPU interface is configured to communicate with a CPU, and an internal memory communicates with the first data port interface and the second data port interface. A memory management unit is provided, including an external memory interface, for communicating data from at least one of the first data port interface and the second data port interface and an external memory. A communication channel is provided, for communicating data and messaging information between the first data port interface, the second data port interface, the internal memory, and the memory management unit.

Abstract: A system for measuring power of a circuit on a printed circuit board (PCB) including first and second circuits, a power strip, a power plane, and a calibration strip. The power strip is connected to the power plane to the first circuit, is embedded in the PCB during the manufacturing process, and also has at least two vias for measuring a voltage drop. The calibration strip is also embedded in the PCB during the manufacturing process and has at least two vias for measuring a voltage drop. The second circuit is configured to measure a voltage drop across the power strip as a first voltage and a voltage drop across the calibration strip as a second voltage, and to calculate the power being fed to the first circuit based on the first voltage and the second voltage.

Abstract: A method for refreshing data in a circuit element included in a dynamic register. A static loop is coupled to the circuit element as a feedback path from the output terminal to the input terminal of the circuit element. A control signal is provided to the static loop. The static loop is activated via the control signal to refresh the data in the circuit element.

Abstract: A graphics integrated circuit chip is used in a set-top box for controlling a television display. The graphics chip processes analog video input, digital video input, a graphics input and an audio input simultaneously. The chip includes a display engine that processes graphics images organized as windows. The display engine processes graphics images formatted in any one of a plurality of formats including a color look up table (CLUT) format. A color look-up (CLUT) table loading mechanism preferably facilitates the transfer of real-time CLUT table data during graphics composition. The loading mechanism may be triggered by a window descriptor that contains a color look-up table load command.

Abstract: A cable modem system and method are provided for using a data compression dictionary to transmit compressed payload data in a DOCSIS network while utilizing conventional cable modem termination system (CMTS) equipment. A cable modem system in accordance with the invention includes a cable modem and a CMTS adapted to send and receive compressed payload data. In one example, the cable modem is adapted to compress PDU payload data using a data compression dictionary and the CMTS is adapted to reconstruct the compressed PDU payload data that is received from the cable modem.

Abstract: A system and method for providing a sort in a computer system is disclosed. The sort is based on a plurality of values of a key. Each of the plurality of items has an associated value of the plurality of values. The method and system include providing a new item of the plurality of items to a plurality of sort cells. The new item includes a new value of the plurality of values. The plurality of sort cells is for sorting the plurality of items. Each sort cell is for sorting a corresponding item of the plurality of items. The corresponding item has a corresponding value of the plurality of values. The method and system further include comparing the new value to the corresponding value for each of the plurality of sort cells to determine whether to retain the corresponding item. Each of the plurality of sort cells retains the corresponding item if the corresponding item is to be retained.

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: A method for enhancing the bit rate and/or margin at which quadrature amplitude modulation (QAM) communication is performed includes the steps of varying a spectral allocation and constellation size with which communication is performed, so as to define a combination of spectral allocation and constellation size at which the bit rate and/or margin are enhanced. The spectral allocation can be varied by varying a stop frequency thereof, while maintaining a substantially constant start frequency, so as to mitigate undesirable high frequency content of the bandwidth. Alternatively, both start and stop frequencies may be varied.

Abstract: A programmable divider includes a synchronous counter configured to process an input clock signal and produce first output signals in response the input clock signal. A number of logic devices are coupled to the synchronous counter and configurable to receive the first output signals and correspondingly produce second output signals. Also included is a multiplexer that is configured to receive the second output signals and has an output coupled to an input of the synchronous counter. In the programmable divider, characteristics of the synchronous counter are selectable based upon a particular number of the logic devices configured.

Abstract: An adaptive electronic transmission signal cancellation circuit for separating transmit data from receive data in a bidirectional communication system operating in full duplex mode is disclosed. The output of a main transmitter responsive to a first bias current is connected to the output of a receiver through an internal resistor. A first replica transmitter responsive to a second bias current and matched to the main transmitter current gain and rise/fall time characteristics is connected to the input terminal of the receiver, and produces a cancellation voltage between the output terminal of the main transmitter and the input terminal of the receiver as a function of the second bias current and the internal resistor.

Abstract: A method and a system for decoding information signals encoded by a multi-state encoding architecture and transmitted over a multi-dimensional transmission channel by computing a distance of a received word from a codeword. One-dimensional (1D) input signals are detected in a symbol decoder, implemented using look-up tables, to produce a pair of 1D errors, with each representing a distance metric between the input signal and a symbol in one of two disjoint symbol-subsets. The symbol decoder is implemented as a pair of slicers, each detecting an input signal with respect to one of two disjoint symbol-subsets. A third slicer detects the input with respect to the union of the two disjoint symbol-subsets. Decisions from the first, second and third slicers are processed to define 1D square error terms expressed in Hamming metrics. Reduced bit count error terms allow follow-on error processing to be performed with a minimum of computational complexity.

Abstract: The present invention provides a frequency-diverse single-carrier modulation scheme that extends the usable SNR range of severely distorted channels. This scheme is advantageous for applications in which when the SNR is low and the transmitted spectrum contains unusable regions (e.g., spectral nulls due to radio-frequency interference ingress or egress). In one embodiment, the symbol baud rate is selected in order that unusable portions of the frequency response of the transmission channel are mapped onto usable portions of the frequency response of the transmission channel.