Maxlinear, Inc.

Ioannis Spyropoulos

Anand Anandakumar

Maxime Leclercq

Nishant Kumar

Curtis Ling

Meetul Parikh

Mario Milicevic

Yves Rasse

A calibration system comprises control circuitry and waveform capture circuitry. The control circuitry selects a first calibration waveform for input to a digital predistortion circuit of a transmitter. The capture circuitry captures a first waveform output by the transmitter in response to the first calibration waveform. The control circuitry compares the first calibration waveform to the captured first waveform. The control circuitry selects a first one of a plurality of mapping circuit configurations based on the result of the comparison, wherein the mapping circuit is configured to map outputs of a plurality of delay circuits among inputs of a plurality of filter taps. The control circuitry stores the one of the mapping circuit configurations in nonvolatile memory associated with the transmitter.

Multi-waveform digital predistortion calibration

A system comprises a digital predistortion circuit comprising: a first quantity of delay circuits configured to delay a signal to be predistorted; a second quantity of filter tap circuits, wherein the second quantity is smaller than the first quantity; and a delay-to-filter-taps mapping circuit that is operable to map each output of a first subset of the delay circuits to a corresponding input of the filter tap circuits. The system may comprise circuitry operable to select which of the first quantity of delay circuits is in the first subset. The selection of which of the first quantity of delay circuits is in the first subset may be based on a temperature measurement. The digital predistortion circuit may comprise cross-term generation circuitry operable to generate cross-term signals corresponding to the cross products of multiple, differently-delayed versions of a signal input to the digital predistortion circuit.

Reconfigurable digital predistortion circuit

A transmitter is configured to generate a DOCSIS signal for transmission onto a frequency-selective coaxial cable. The transmitter comprises a first reverse tilt filter circuit, a digital predistortion circuit, a forward tilt filter, a wideband equalizer, a second reverse tilt filter, and a power amplifier. The responses of the tilt filters may be set based on the frequency response of the frequency-selective coaxial cable to which the transmitter is intended to be coupled. The predistortion circuit may compensate for distortion introduced by circuitry of the transmitter. The equalizer circuit may be operable to compensate for undesired linear response of other circuitry of the transmitter.

Digital predistortion for a frequency-selective channel

An electronic receiver may generate a differential detection sequence based on a received symbol sequence and based on a m-symbol delayed version of the received symbol sequence, where in is an integer greater than 1. The particular differential detection sequence may be a result of an element-by-element multiplication of the particular received symbol sequence and the conjugate of an in-symbol delayed version of the particular received symbol sequence. The receiver may calculate differential decision metrics based on the differential detection sequence and based on a set of differential symbol sequences generated from the set of possible transmitted symbol sequences. The receiver may generate a decision as to which of a set of possible transmitted symbol sequences resulted in the received symbol sequence, where the decision is based on the differential decision metrics and the set of possible transmitted symbols sequences.

Non-coherent multi-symbol-delay differential detector

Aspects of a method and system for feedback during optical communications are provided. In one embodiment, a system for optical communications comprises a predistortion module, a feedback subsystem, a transmit optical subsystem, and an external modulator. The predistortion module is operable to receive an input digital signal and modify the input digital signal to produce a digital predistorted signal. The transmit optical subsystem is operable to generate an optical signal from the digital predistorted signal. The modification of the input digital signal is dynamically controlled by the feedback subsystem according to one or more characteristics of the optical signal as determined by the feedback subsystem. The amplitude of the external modulator output is also dynamically controlled by the feedback subsystem.

Hybrid direct-modulated/external modulation optical transceiver

An electronic receiver may generate a differential detection sequence based on a received symbol sequence and based on a m-symbol delayed version of the received symbol sequence, where m is an integer greater than 1. The particular differential detection sequence may be a result of an element-by-element multiplication of the particular received symbol sequence and the conjugate of an m-symbol delayed version of the particular received symbol sequence. The receiver may calculate differential decision metrics based on the differential detection sequence and based on a set of differential symbol sequences generated from the set of possible transmitted symbol sequences. The receiver may generate a decision as to which of a set of possible transmitted symbol sequences resulted in the received symbol sequence, where the decision is based on the differential decision metrics and the set of possible transmitted symbols sequences.

Aspects of a method and system for feedback during optical communications are provided. In one embodiment, a system for optical communications comprises a digital-to-analog converter (DAC), a driver, and a transmit optical subsystem. The DAC is operable to receive a digital code of a plurality of digital codes and output an analog current signal having an analog current level of a plurality of analog current levels. The driver is operable to condition the analog current signal output from the digital-to-analog converter. The transmit optical subsystem is operable to generate an optical signal from the conditioned analog current signal. A digital modification of an input digital signal is dynamically controlled by a feedback path according to one or more characteristics of the optical signal. The one or more characteristics comprise a nonlinearity that may be temperature dependent.

Transmit optical sub-assembly with local feedback

A signal receiver may be configured to determine when signal generation adjustments directed to particular components of signals received by the signal receiver, cause performance changes relating to effects of the signal generation adjustments on other components of the received signals. Operations of the signal receiver may then be controlled based on the performance changes, to mitigate at least some of the effects on the one or more other components of the signals. The performance changes may comprise amplitude glitches, phase glitches, and/or bit or packet errors. The signal generation adjustments may comprise channel-to-frequency re-assignment. Controlling operations of the signal receiver may comprise adjusting such parameters as amplification gain and/or tracking loop bandwidth, and/or determining whether (or not) to ignore bit/packet errors.

Method and system for receiver configuration based on a priori knowledge of noise

Methods and systems for repurposing of a global navigation satellite system receiver for receiving low-earth orbit (LEO) communication satellite timing signals may comprise receiving a medium Earth orbit (MEO) satellite signal and/or a LEO signal in a receiver of the communication device. The MEO or LEO signal may be down-converted, and a position of the communication device may be calculated utilizing the down-converted signal. The signal may be down-converted utilizing a local oscillator signal generated by a phase locked loop (PLL), which may be delta-sigma modulated via a fractional-N divider. A clock signal may be communicated to the PLL utilizing a temperature-compensated crystal oscillator. The signal may be down-converted to an intermediate frequency or down-converted directly to baseband frequencies. The signal may be processed utilizing surface acoustic wave (SAW) filters. In-phase and quadrature signals may be processed in the RF path utilizing a two-stage polyphase filter.

Method and system for repurposing of a global navigation satellite system receiver for receiving low-earth orbit communication satellite signals

A GPS receiver includes an RF front end for acquiring and tracking a satellite signal and a baseband processor configured to preserve power. The baseband processor includes a GPS engine configured to process the satellite signal and generate a PVT fix, a power supervisory module for receiving the PVT fix, and a user state module that determines an environmental state, wherein the power supervisory module may power down the GPS receiver for a period of time based on a result of the determined environment state. The baseband processor also includes a time-based management module that adjusts the TCXO in response to the determined environmental state. The GPS receiver includes a plurality of operation modes, each of which is associated with a plurality of tracking profiles.

GPS baseband controller architecture

Methods and systems for a dual mode global navigation satellite system may comprise selectively enabling a medium Earth orbit (MEO) radio frequency (RF) path and a low Earth orbit (LEO) RF path in a wireless communication device to receive RF satellite signals. The signals may be processed to determine a position of the wireless device. The signals may be digitized and buffered before further processing. The RF paths may be time-division duplexed by the selective enabling of the MEO and LEO paths. Acquisition and tracking modules in the MEO RF path may be blanked when the LEO RF path is enabled. The MEO RF path may be powered down when the LEO RF path is enabled. The signals may be down-converted to an intermediate frequency before down-converting to baseband frequencies or may be down-converted directly to baseband frequencies. In-phase and quadrature signals may be processed.

Method and system for a dual mode global navigation satellite system

Methods and systems for femtocell positioning using low Earth orbit (LEO) satellite signals may comprise receiving LEO RF satellite signals utilizing a LEO satellite signal receiver path when medium Earth orbit (MEO) signals are attenuated below a threshold needed for positioning purposes. A position of said wireless communication device (WCD) may be measured based on the received LEO RF satellite signals. The measured position of the WCD may be compared to a threshold radius defined by a stored initial position. Wireless communication services to the other WCDs may be enabled when the measured position is within the threshold radius. Reentry of the stored initial position may be requested when the measured position is outside of the threshold radius. The WCD may be disabled when the measured position of the WCD falls outside of the threshold radius more than a predetermined number of times.

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La Jolla, CA, United States of America

Ioannis Spyropoulos