Globespan, Inc.

Globespan Virata Corporation

Conexant, Inc.

Beijing Vango Technologies, Inc.

Vango (hangzhou) Technologies Inc.

Nianxiong Tan

Frode Larsen

Peter D Keller

Mikael Gustavsson

Arnold Muralt

Daniel Amrany

Brian Horng

Christian Eichrodt

Jung-Lung Lin

James J Zhao

Sam Olu George

Francis M Caster, Ii

Ronghua Wang

Min Shen

Devices and methods for accurately realizing the integration functions, in particular for energy metering systems using a Rogowski coil, are disclosed. In this regard, exemplary embodiments of the present invention may be constructed as two stable filters for the current (I) and voltage (U) channel. In the analog realization form, the transfer function of the voltage channel may be constructed as a high-pass filter function with at least one zero at the origin, while the transfer function of the current channel may be constructed as the multiplication of the high-pass filter function of the voltage channel and the ideal analog integration function. In the digital realization form, the transfer function of the filter for the voltage channel may be constructed as a high-pass filter function with zero(s) at the same location(s) as the pole(s) of the digital integration function, while the transfer function of the filter for the current channel is the multiplication of the high-pass filter function of the voltage channel and the digital integration function.

Integration methods for energy metering systems using a Rogowski coil

An analog front-end circuit and method that supports multiple digital subscriber line (DSL) standards, including asymmetric digital subscriber line (ADSL) and very-high speed digital subscriber line (VDSL) is disclosed. The circuit incorporates multiple circuit blocks that can be selectively included into the transmit and receive paths of a DSL signal. It also permits selectable gain settings for signal amplifiers, and frequency bandwidth for signal filters that may be included in the transmit and receive paths. The receive path includes an analog-to-digital converter (ADC) that operates close to and exceeds the Nyquist sampling rate.

Wide-band analog front-end for DSL applications

Devices and method for effectively filtering a signal, particularly for a communication system, are disclosed. In this regard, an exemplary embodiment of the present invention may be construed as an AFE that includes a high-pass receive filter for a communication system. The filter includes an AC-coupled capacitive input and a plurality of RC integrators. At least one of the plurality of RC integrators includes a damping resistor in parallel with a feedback capacitor and a switch for enabling the damping resistor, such that when the damping resistor is enabled, the at least one RC integrator is damped so as to reduce DC instability.

Low power active filter and method

The present invention relates to improved ADC buffers and AFEs for high frequency applications, such as VDSL. The present invention can also be programmably configured for other xDSL applications. In this regard, a buffer circuit for a high-bandwidth analog-to-digital converter (ADC) includes a first unity-gain buffer configured to receive an analog input signal. The first unity-gain buffer includes a MOSFET differential amplifier with a current mirror load and a transient-reduction network electrically interconnected with the MOSFET differential amplifier and configured to reduce transient energy emitted by the ADC. The buffer circuit also includes a second unity-gain buffer cascaded to the first unity-gain buffer and configured to provide the analog input signal from the first unity-gain buffer to the ADC.

Buffer circuit for a high-bandwidth analog to digital converter

Methods and systems for tuning an RC continuous-time filter are disclosed. In this regard a representative system for tuning an RC continuous-time filter includes a coarse-tuned resistive element coupled to an input of the filter for varying the cut-off frequency of the filter based upon process variations. The system also includes a MOSFET transistor coupled to the resistive element. The MOSFET transistor provides a resistance dependent upon a voltage offset provided to the gate of the transistor, wherein the resistance of the transistor offsets an adjustment in the resistance of the resistive element caused by temperature variations. The system also includes a voltage offset generator configured to provide the voltage offset to the transistor.

System and method for tuning an RC continuous-time filter

A SINC filter for an oversampling Sigma-Delta digital to analog converter (OSDAC) having a cascaded construction that results in reduced sensitivity to capacitor mismatch. Specifically, the SINC filter circuit filter may be defined by a transfer function H(z), which is further defined by first constituent transfer functions H (z) and H (z). The constituent transfer functions may be implemented in a cascaded fashion. Preferably, one of the cascaded sections includes a resistor string that defines a plurality of reference voltages. A plurality of switching elements are configured to controllably switch these reference voltages to a capacitor of a tap.

High performance switched-capacitor filter for oversampling Sigma-Delta digital to analog converters

In general, the multi-mode analog front-end provides an internal line driver and hybrid, as well as numerous functions, in order to provide a close to optimum solution for all digital subscriber line applications. The functions provided for by the analog front-end include; programmable hybrid attenuation; onboard amplifiers for driving external transmit and receive filters; a line driver with programmable drive and gain; programmable RC-filters capable of calibration via an internal loop-back under digital control; a programmable switched-capacitor filter for tracking the over sampling rate used by a digital signal processor; internal testing functions; a high frequency boost circuit; a dual input peak detector; selectable data rates; and a programmable data interface. The analog front-end allows for use of particular blocks within the analog front-end particular to the functions necessary to compensate for a particular digital subscriber line application.

Multi-mode analog front-end

An improved SC filter for OSDACs for asynchronous digital subscriber line (ADSL) applications. More specifically, an improved switched-capacitance (SC) filter for an over-sampled digital to analog converter intended for use in a multi-mode analog front end for a host of ADSL applications. The SC filter is configured for low power consumption and for a low-ambient noise floor across the frequencies of interest. The SC filter is further configured to drive a resistive load of a few kohms and for low signal distortion. The SC filter lowers power consumption by decimating the input waveform and reducing the number of operational amplifiers in the circuit.

High performance switched-capacitor filter for oversampling sigma-delta digital to analog converters

The disclosure is generally directed to an improved structure for a decimation filter. More specifically, the disclosure includes a method and apparatus for decimating an oversampled signal at the input, which is the output of an oversampling analog-to-digital converter. In accordance with one aspect of the system, an apparatus is provided for decimating an oversampled signal. The apparatus includes at least one non-recursive decimator. Specifically, the at least one non-recursive decimator is configured to receive the oversampled input signal defined by a first sampling frequency. This at least one non-recursive decimator is further configured to generate a output having a second sampling frequency. The apparatus further includes a recursive decimator. The recursive decimator is configured to receive the output of the at least one non-recursive decimator and generate an output having third sampling frequency. It will be appreciated that the second sampling frequency output from the non-recursive decimator is less than the sampling frequency of the oversampled input signal, and further that the third sampling frequency is less that the second sampling frequency. In accordance with another aspect of the disclosure, a method is provided for decimating an oversampled signal. Broadly, the method includes the steps of decimating the oversampled signal in accordance with a non-recursive decimation algorithm to generate an interim decimated signal, and decimating the interim decimated signal in accordance with a recursive decimation algorithm to generate a final decimated signal.

Decimation filter for oversampling analog-to digital converter

A system and method for force-starting a voltage and current controlled element is disclosed. In a simplified embodiment, a power source is coupled to the controlled element via a start-up circuit. The start-up circuit supplies a current, or voltage, to the controlled element, responsive to the voltage or current level at a specified node being below a threshold level. Preferably, two diode-connected devices may be utilized, thereby providing current forcing capability when the voltage level at the specified node is below a threshold voltage level, as specified by the diode-connected devices.

System and method for starting voltage and current controlled elements

In general, the reference voltage stabilizer provides a system and method of stabilizing a reference voltage regardless of the sampling rate of a sample data system. An amplifier is utilized to amplify the reference voltage so as to maintain voltage level by stabilizing and isolating the initial reference voltage. A programmable current is utilized to modify the amplified reference voltage, thereby compensating for adjustment in current level of the reference voltage caused by system sampling. The programmable current may also be utilized to compensate for reference voltage errors occurring before amplification, by adding an intentional offset between required sink and source currents, and the current supplied by the programmable current.

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Laguna Niguel, CA, United States of America

Nianxiong Tan