Direct Conversion Tuner Architecture With Agile Clock Spur Avoidance

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Solution Overview

Problem

Existing receiver configurations for television broadcast signals struggle to support multiple analog and digital broadcast standards due to complex tuner architectures, high component counts, and performance issues such as dynamic range and channel cross modulation, which hinder integration and increase power consumption.

Innovation Solution

A multimode tuner architecture implementing direct frequency conversion with a single integrated circuit, incorporating a low noise amplifier, analog and digital channel filters, and demodulators, along with in-phase and quadrature equalization, to provide flexible operation across various broadcast standards while minimizing noise and spurs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a multi-conversion tuner architecture is used to support multiple broadcast standards, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improvesupport for multiple broadcast standardsVSAvoidtuner architecture complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a universal direct conversion tuner architecture that can process both analog and digital broadcast standards through a single integrated circuit. The system uses configurable filters and demodulators that can be dynamically adjusted to handle different modulation schemes (QAM, OFDM, VSB) and broadcast standards (ATSC, DVB-T, ISDB-T, DTMB), eliminating the need for separate dedicated tuners for each standard.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines multiple previously separate components (tuner, filters, demodulators for both analog and digital) into a single integrated direct conversion tuner circuit. This merging reduces the overall component count and simplifies the architecture while maintaining the ability to support multiple broadcast standards through software-configurable parameters.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If separate signal processing paths are provided for analog and digital signals, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesignal processing reliabilityVSAvoidsignal processing path complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the signal processing into distinct configurable modules (tuner front-end, I/Q demodulation, digital signal processing, filtering stages) that can be independently optimized for different broadcast standards while sharing common infrastructure. This modular segmentation allows reliable processing of both analog and digital signals through the same physical path with dynamically adjusted parameters.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If channel filters with precise pass-band characteristics are used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvechannel selection precisionVSAvoidfilter configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs digitally configurable filters whose parameters (cutoff frequencies, pass-band width, center frequency) can be dynamically changed through software control. This allows the same physical filter hardware to achieve precise channel selection for different broadcast standards by reconfiguring its transfer function, eliminating the need for multiple dedicated filters.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If a highly integrated configuration is implemented, then ease of manufacture is improved, but spurious signals increase

Engineering Contradiction:

Improveintegration levelVSAvoidspurious signals

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent introduces carefully designed intermediate filtering stages and shielding structures within the integrated circuit to isolate spurious signal generation points from sensitive signal paths. These intermediary elements (such as isolation capacitors, ground planes, and intermediate filters) prevent coupling between high-frequency switching nodes and low-frequency signal processing nodes, thereby suppressing spurious signals despite high integration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8586461B2Systems and methods providing spur avoidance in a direct conversion tuner architecture

Publication Date: 2013.11.19 QUALCOMM INC

AI summary

Systems and methods which provide a multimode tuner architecture implementing direct frequency conversion are shown. Embodiments provide a highly integrated configuration wherein low noise amplifier, tuner, analog and digital channel filter, and analog demodulator functionality are provided in a single integrated circuit. A LNA of embodiments implements a multi-path configuration with seamless switching to provide desired gain control while meeting noise and linearity design parameters. Embodiments of the invention implement in-phase and quadrature (IQ) equalization and a multimode channelization filter architecture to facilitate the use of direct frequency conversion. Embodiments implement spur avoidance techniques for improving tuner system operation and output using a clock signal generation architecture in which a system clock, sampling clock frequencies, local oscillator (LO) reference clock frequencies, and/or the like are dynamically movable.