Direct Conversion Tuner Spur Avoidance for Multistandard TV Reception
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Solution Overview
Problem
Existing television receiver configurations face challenges in supporting 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 simplification.
Innovation Solution
A multimode tuner architecture implementing direct frequency conversion with a single integrated circuit, incorporating low noise amplifiers, channel filters, and demodulators, along with digital baseband processing for IQ equalization and spur avoidance techniques, enabling operation with various broadcast standards and reducing component count.
Engineering Contradictions & Design Principles
Engineering 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
Solution Approach 1:
The patent implements a universal direct conversion tuner architecture that can process both analog and digital broadcast signals through a single frequency conversion path. The tuner uses a common intermediate frequency (IF) of 40 MHz for both signal types, with a single mixer, local oscillator, and filter chain. The architecture achieves multi-functionality by using a programmable digital signal processor that can be configured to handle different modulation schemes and demodulation algorithms, eliminating the need for separate tuner circuits for analog and digital standards.
2Measurement precision
If separate signal processing paths are provided for analog and digital signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the analog and digital signal processing paths into a single unified architecture. Both analog and digital broadcast signals undergo the same frequency conversion process through a shared mixer and local oscillator, and both pass through a common 40 MHz IF filter. The merged paths converge at the digital signal processor, which performs both analog demodulation and digital demodulation functions. This consolidation reduces component count while maintaining processing accuracy through dedicated digital signal processing algorithms.
3Measurement precision
If channel filters with precise pass-band characteristics are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs digitally programmable filter parameters that can be dynamically adjusted based on the selected broadcast standard and channel frequency. The 40 MHz IF filter and subsequent digital filters have their cutoff frequencies, pass-band widths, and attenuation characteristics programmably configured through digital control registers. This allows the same physical filter hardware to achieve precise channel selection for different analog standards (NTSC, PAL, SECAM) and digital standards (ATSC, DVB-T, ISDB-T) without requiring multiple dedicated filters.
4Adaptability or versatility
If multiple channel filters are provided for different broadcast standards, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamically reconfigurable filter characteristics that adapt to different broadcast standards in real-time. The filter parameters including center frequency, bandwidth, and attenuation are controlled by digital registers that can be programmed based on the detected or selected broadcast standard. This dynamic reconfiguration allows a single filter hardware implementation to provide the precise channel selection required for analog standards with vestigial sideband modulation and digital standards with different channel spacings, eliminating the need for multiple static filters.
Data Source
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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.