Silicon Laboratories Inc.

Crystal Semiconductor Corporation

Other

Cirrus Logic Inc.

Andrew W Krone

David R Welland

Navdeep S Sooch

Jeffrey William Scott

Timothy Joseph Dupuis

Mitchell Reid

Ramin Khoini-Poorfard

Jerrell P Hein

John James Paulos

Jason Powell Rhode

Richard Bocock

Gautham Devendra Kamath

Nicholas R Van Bavel

Jeffery W Scott

In one embodiment, the present invention includes a method for filtering an incoming signal in a channel filter of an automatic frequency control (AFC) loop to obtain a filtered incoming signal, generating a frequency offset from the filtered incoming signal in the AFC loop, removing the frequency offset from the incoming signal to obtain an adjusted signal, and providing the adjusted signal to an input of the channel filter.

Providing channel filtering in an automatic frequency control path

Receiver architectures and associated methods are disclosed that provide initial analog coarse tuning of desired channels within a received signal spectrum, such as a set-top box signal spectrum for satellite communications. These architectures provide significant advantages over prior direct down-conversion (DDC) architectures and low intermediate-frequency (IF) architectures, particularly where two tuners are desired on the same integrated circuit. Rather than using a low-IF frequency or directly converting the desired channel frequency to DC, initial coarse tuning provided by analog coarse tuning circuitry allows for a conversion to a frequency range around DC. This coarse tuning circuitry can be implemented, for example, using a large-step local oscillator (LO) that provides a coarse tune analog mixing signal. Once mixed down, the desired channel may then be fine-tuned through digital processing, such as through the use of a wide-band analog-to-digital converter (ADC) or a narrow-band tunable bandpass ADC.

Receiver architectures utilizing coarse analog tuning and associated methods

In one embodiment, the present invention includes a method for injecting a gain compensation value into a signal path of a receiver for a predetermined time when a change to a control value for an amplifier of the receiver occurs. This gain compensation value may be used to at least substantially remove a gain change caused by the change to the control value, improving audio performance by reducing or removing audible artifacts caused by the gain change.

Reducing noise during a gain change

Multi-tuner receiver architectures and associated methods are disclosed that provide initial analog coarse tuning of desired channels within a received signal spectrum, such as transponder channels within a set-top box signal spectrum for satellite communications. These multi-tuner satellite receiver architectures provide significant advantages over prior direct down-conversion (DDC) architectures and low intermediate-frequency (IF) architectures, particularly where two tuners are desired on the same integrated circuit. Rather than using a low-IF frequency or directly converting the desired channel frequency to DC, initial coarse tuning provided by analog coarse tuning circuitry allows for a conversion to a frequency range around DC. This coarse tuning circuitry can be implemented, for example, using a large-step local oscillator (LO) that provides a coarse tune analog mixing signal. Once mixed down, the desired channel may then be fine-tuned through digital processing, such as through the use of a wide-band analog-to-digital converter (ADC) or a narrow-band tunable bandpass ADC.

Integrated multi-tuner satellite receiver architecture and associated method

A communication isolation system is provided that may employ error correction techniques for the data communicated across an isolation barrier used for connecting electronic circuitry to a communication line. In one embodiment, each data bit to be transmitted to or from the phone line may be transmitted three times across an isolation barrier so that it is possible to withstand a single electronic fast transient event. In another embodiment, the isolation barrier may be a capacitive isolation barrier. In another embodiment, the three transmissions of the data bit may be received across the isolation barrier and delay elements utilized to provide the data bits to a logic circuit in a synchronized fashion so that the three data bits may be compared to determine the error corrected data.

Error correction of data across an isolation barrier

A low noise amplifier () includes a first transconductance device () having a control electrode for receiving a first input signal, and a first current electrode; a first load device () having a first terminal coupled to a first power supply voltage terminal and a second terminal coupled to the first current electrode of the first transconductance device () and forming a first output voltage signal; a second transconductance device () having a control electrode for receiving a second input signal, and a second current electrode; a second load device () having a first terminal coupled to the first power supply voltage terminal and a second terminal coupled to the first current electrode of the second transconductance device () and forming a second output voltage signal; and an attenuation device () coupled between the first current electrodes of the first () and second () transconductance devices and having a control input terminal for receiving a control voltage thereon.

Radio frequency low noise amplifier with automatic gain control

An improved digital capacitive isolation barrier system is provided that is suitable for use in a telephone or modem where the locally powered circuits must be effectively isolated from the public telephone system, while permitting data transfer across the barrier. In particular, an automatic ADC offset calibration system is provided for determining the magnitude of the ADC offset signal required in the system during a calibration operation, and for providing the calibrated ADC offset signal during normal operation of the isolation barrier system. A modified hybrid circuit is provided for isolating the system input from the telephone line during calibration, and for completing the calibration loop. Fixed bias signals are also provided for the ADC and for a DAC in the system. In a preferred embodiment, the ADC is located on the isolated side of the isolation barrier, while the integrator and register that determine and hold the offset signal are located on the powered side of the isolation barrier.

Digital isolation system with hybrid circuit in ADC calibration loop

Digital isolation system with ADC offset calibration

A communication system is provided which draws virtually no loop current during a ringing burst and only draws on-hook loop current during the caller ID field. More particularly, ringer burst circuitry may be powered from the user powered circuitry by the transmission of power across the isolation barrier rather than being powered from the phone line. Thus, loop current need not be drawn from the TIP/RING lines during ringer bursts. The isolation barrier may be a capacitive isolation barrier which allows bidirectional communication and extraction of power from signals transmitted across the barrier.

Architecture for minimum loop current during ringing and caller ID

An audio signal processor which modifies audio signal components outside the conventional audio frequency band. The processor includes a Delta Sigma Modulator (DSM) that receives a non-interpolated digital audio signal sampled at a frequency of at least 198 kHz.

Loop current monitor circuitry and method for a communication system

An improved modem architecture and associated method are disclosed that integrate modem functionality and line-side isolation functionality while also providing a modem interface that allows raw data, such as raw pulse-code-modulated (PCM) data, or modem data to be selectively communicated through a serial interface.

Integrated modem and line-isolation circuitry with selective raw data or modem data communication and associated method

Methods and architectures for tuning bandpass analog-to-digital converters (ADCs) are disclosed that can be used, for example, with receiver architectures and associated methods that are also disclosed. The notch of the bandpass ADC can be tuned to the desired channel frequency by adjusting the notch to reduce noise energy in the output signal through a feedback process that adjusts the tuning signal. In addition, a master-slave approach can be implemented to tune a tunable bandpass filter configured as a slave circuit based upon the tuning adjustments made to the master bandpass ADC circuit. In addition, receiver architectures and associated methods are disclosed that utilize coarse analog tune circuitry to provide initial analog coarse tuning of desired channels within a received spectrum signal, such as a set-top box signal spectrum for satellite communications.

Method for tuning a bandpass analog-to-digital converter and associated architecture

An improved modem architecture and associated method are disclosed that integrate modem functionality and line-side isolation functionality while also providing flow control of internal data between an isolation interface, digital-signal-processor (DSP) circuitry, and an analog input. The integrated modem and line-isolation circuit may also have an analog output for which data flow control is also provided.

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Austin, TX, United States of America

Andrew W Krone