Broadcom Corporation

Ardie Venes

Hongwei Wang

Xicheng Jiang

Donald George McMullin

Derek Hing-Sang Tam

A cable network gateway receives a downstream broadband signal via service provider cabling at an interface. An Analog to Digital Converter (ADC) converts the downstream broadband signal to a digital downstream broadband signal. A digital filter attenuates an upper spectrum from the digital downstream broadband signal to produce a filtered digitized downstream broadband signal. An in-home communications transceiver produces a digital in-home communications signal that overlaps the upper spectrum. Summing circuitry sums the filtered digitized downstream broadband signal with the digital in-home communications signal to produce a combined digital signal. A Digital to Analog Converter (DAC) converts the combined digital signal to a combined analog signal and an in-home cable interface transmits the combined analog signal via in-home cabling. The downstream broadband signal may be a Data over Cable System Interface Specification (DOCSIS) 3.0/3.1 signal and the digital in-home communications signal comprises a Multimedia over Coaxial Alliance (MoCA) signal.

Cable network gateway with digital DOCSIS/MoCA bridge

An output stage protection system for protecting NMOS devices in an integrated circuit (IC) output stage during normal operations and power up/power down. In an embodiment, the output stage includes a pair of relatively low voltage NMOS devices coupled to a current source and IC core outputs. A first pair of relatively high voltage NMOS devices is coupled to the relatively low voltage pair and a biasing circuit. A second pair of relatively high voltage NMOS devices is coupled to a resistor, the first pair, and first and second output nodes, respectively. One or more diodes are coupled in series between the first and second output nodes and the resistor. In an embodiment, the output stage protection system protects NMOS devices in the output stage from electrostatic discharge (ESD). Input/output (I/O) pad ESD protection circuits are coupled to the I/O pads and include a clamp coupled to a local net.

Circuit output stage protection system

A design for a differential amplifier with a large input common mode signal range. The differential amplifier comprises two differential pairs, each having two amplifying MOSFETs. A source follower is connected to the gate terminal of each amplifying MOSFET in one of the differential pairs. A differential signal applied to the differential amplifier comprises two separate signal. Each separate signal is applied to the gate terminals of both the amplifying MOSFET in the differential pair not driven by the source follower and the driven MOSFET of the source follower. The differential amplifier further comprises a pair of switch MOSFETs connected to a current source MOSFET. The switch MOSFETs act to control the distribution of the total current flowing from the current source MOSFET and, consequently, to determine which differential pair works dominantly to amplify the input signals. Each source follower acts to offset the voltage of its input signal to compensate for the range loss due to the bias voltages and the threshold voltages within the differential amplifier.

Differential amplifier with large input common mode signal range

A programmable gain amplifier with three stages uses fine steps, has a large gain range, and is monotonic. The first stage comprises several amplifiers, each including a resistive feedback loop. The feedback loop comprises a series of resistors, with each resistor acting as a tap. Since the number of resistors in the loop is unchanging, monotonicity and stability is guaranteed when resistance is increased using successive taps. A switch system connects two taps at a time to an interpolation stage. Each of these taps corresponds to a specific resistor level, and thus a gain level. The interpolation stage uses a plurality of current sources inside a feedback amplifier to control the interpolation, in order to provide fine gain steps.

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Laguna Niguel, CA, United States of America

Ardie Venes