US 2011/0255011 A1Published application

All Digital Front-End Architecture for Television with Sigma-Delta ADC Input

AssigneeNewport Media, Inc.

InventorsYongru Gu, Nabil Yousef Wasily

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Abstract

A digital front-end architecture for television receivers with sigma-delta ADC input. An input digital signal is fed to the architecture and the gain is controlled by a gain stage. In the first method, the gain stage is controlled by a first AGC. Here, the gain is increased if the first threshold value is larger than the magnitude of a complex phase-locked loop (CPLL) output, and the gain is decreased if the first threshold value is lower than the magnitude of the CPLL output. In the second method, the gain is controlled through a second AGC. The gain is controlled by increasing the gain if the second threshold value is larger than a line peak of the moving average filter output, and the gain is decreased if the second threshold value is lower than the peak. The second threshold value and the peak are compared in a peak search block.

Claims20

Dependent claims

A method of controlling a gain in an input digital signal received from a sigma-delta analog-to-digital converter (ΣΔADC) that converts an analog television signal from a tuner to said input digital signal for an analog television receiver, wherein said tuner introduces a DC component to said analog television signal, wherein said input digital signal comprises a video carrier, wherein said video carrier comprising a Luma carrier, and wherein said analog television receiver comprising:

a first cascaded integrator comb (CIC) filter that receives said input digital signal from said ΣΔADC;
a first down-sampler operatively connected to said first CIC filter, said first down-sampler comprising a down sampling factor of two;
a half-band filter operatively connected to said first down-sampler;
a second down-sampler operatively connected to said half-band filter;
and
a first adjacent channel interference (ACI) rejection filter operatively connected to said second down-sampler, wherein said first ACI rejection filter comprises an interpolated filter that provides a sharp transition band performance, wherein said interpolated filter comprises a zero-coefficient for alternate taps,
wherein said method comprises:
smoothing, in a de-ripple (De-RPL) filter, an in-band ripple in a filter response from said CIC filter;
removing, in a digital DC offset cancellation block, said DC component introduced by said tuner;
removing, in a programmable notch filter, sinusoid spurs at a plurality of multiple locations in said input digital signal;
receiving, in a gain stage, at least one gain from any of a first automatic gain control block (AGC) and a second AGC block;
detecting, in phase imbalance correction (PIC) circuitry, a correlation between a I and Q components of said video carrier;
removing said correlation;
detecting, in amplitude correction (AIC) circuitry, an imbalance between the magnitudes of said I and Q components;
correcting said imbalance of said I and Q components;
and
down-mixing, in a direct digital frequency synthesis (DDFS) circuitry, a Luma carrier of said video carrier to approximately DC.

14 more elements

A digital front-end architecture to control a gain of an input digital signal for an analog television (TV) receiver, said digital front-end architecture receives said input digital signal from a Sigma-Delta Analog- to-Digital Converter (ΣΔADC), wherein said ΣΔADC converts an analog TV signal from a tuner to said input digital signal, wherein said tuner introduces a DC component, wherein said input digital signal comprises a video carrier, and wherein said video carrier comprises I and Q components, said digital front-end architecture comprising:

a first cascaded integrator comb (CIC) filter that receives said input digital signal;
a first down sampler operatively connected to said CIC filter that receives an output from said CIC filter, wherein said down sampler comprises a sampling factor of two;
a half-band (HB) filter operatively connected to said first down-sampler;
a second down sampler operatively connected to said HB filter comprising a sampling factor of two;
a first adjacent channel interference (ACI) rejection filter operatively connected to said second down sampler, wherein said first ACI filter comprises an interpolation finite impulse response (FIR) filter that provides a sharp transition band performance, wherein said FIR filter comprises a zero-coefficient for alternate taps;
a second ACI filter operatively connected to said first ACI filter, wherein said second ACI filter provides attenuation for a high frequency response of said first ACI filter;
a configurable de-ripple (De-RPL) filter operatively connected to said second ACI filter, wherein said configurable de-ripple (De-RPL) filter smoothens an in-band ripple in response to said CIC filter;
a digital DC offset cancellation (DCO) unit operatively connected to said De-RPL filter, wherein said DCO unit removes said DC component introduced by said tuner;
a programmable notch filter that removes sinusoid spurs at multiple locations in said input digital signal;
and
a pair of automatic gain control (AGC) blocks that provide an output to adjust said gain of said input digital signal.

8 more elements

A system to control a gain of an input digital signal for analog television (TV) receiver, said system receiving said input digital signal from a Sigma-Delta Analog-to-Digital Converter (ΣΔADC), wherein said ΣΔADC converts an analog TV signal from a tuner to said input digital signal, wherein said tuner introduces a DC component, wherein said input digital signal comprises a video carrier, and wherein said video carrier comprises I and Q components, said system comprising:

a first cascaded integrator comb (CIC) filter that receives said input digital signal from said ΣΔADC;
a first down-sampler operatively connected to said first CIC filter, said first down-sampler comprising a down sampling factor of two;
a half-band filter operatively connected to said first down-sampler;
a second down-sampler operatively connected to said half-band filter;
a first adjacent channel interference (ACI) rejection filter operatively connected to said second down-sampler, wherein said first ACI rejection filter comprises an interpolated filter that provides a sharp transition band performance, wherein said interpolated filter comprises a zero-coefficient for alternate taps;
means for smoothing an in-band ripple in a filter response from said CIC filter;
means for removing said DC component introduced by said tuner;
means for removing sinusoid spurs at a plurality of multiple locations in said input digital signal;
means for receiving at least one gain from at least one of a first automatic gain control block (AGC) and a second AGC block;
means for detecting a correlation between I and Q components of said video carrier and removing said correlation;
means for detecting an imbalance between the magnitudes of said I and Q components and correcting said imbalance of said I and Q components;
means for down-mixing a Luma carrier of said video carrier to approximately DC;
means for converting a vestigial band (VSB) signal to a double side band (DSB) signal;
means for separating an audio signal and a video signal from said double side band (DSB) signal;
means for comparing a magnitude of an output of a complex phase locked-loop (CPLL) block with a first threshold value;
means for searching a peak of every input digital signal from an output of a moving average filter;
and
means for comparing said peak with a second threshold value.

15 more elements

Dependencies are inferred from the claim text.