Multi-Path Low Noise Amplifier for Seamless Tuner Switching
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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 that includes a low noise amplifier, tuner, analog and digital channel filters, and demodulators, utilizing in-phase and quadrature equalization and multimode channelization filters to provide seamless switching and spur avoidance, enabling operation with various broadcast standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate signal processing paths are used for analog and digital broadcast signals, then each path can be optimized for its specific standard, but the device complexity and component count increase significantly
Solution Approach 1:
The patent combines separate analog and digital signal processing paths into a unified direct conversion tuner architecture. A single low IF tuner (4-8 MHz) serves both analog NTSC and digital ATSC standards simultaneously, eliminating the need for separate tuner circuits. The channel selection filter and signal processing components are shared between standards, reducing overall device complexity while maintaining optimized performance for each standard through software-configurable parameters.
Solution Approach 2:
The tuner architecture implements multi-functionality by designing a universal low IF tuner that can process both analog and digital broadcast signals. The same hardware components (tuner, channel filter, demodulator) are configured differently via software to support multiple broadcast standards (NTSC, ATSC, and future standards), allowing one component to perform multiple functions rather than requiring separate dedicated circuits for each standard.
2Adaptability or versatility
If multiple channel filters are provided for different broadcast standards, then each standard can be accommodated, but the component count and integration difficulty increase
Solution Approach 1:
The channel selection filter is implemented as a dynamically reconfigurable component rather than a fixed circuit. The filter's center frequency and bandwidth parameters can be dynamically adjusted via software control to match different broadcast standards (e.g., 6 MHz for ATSC, 7 MHz for NTSC). This dynamic configurability allows a single physical filter component to adapt to multiple standards, eliminating the need for multiple fixed filters and simplifying integration.
Solution Approach 2:
The patent utilizes parameter changes to accommodate different broadcast standards. Key parameters such as intermediate frequency (IF), channel bandwidth, and filter characteristics are modified through software configuration rather than hardware changes. For example, the low IF is set to 4-8 MHz range that can be tuned for different standards, and the channel filter parameters are adjusted accordingly. This approach allows one hardware design to support multiple standards by changing operational parameters.
3Reliability
If high image rejection is achieved through additional filters and image reject mixers, then image rejection performance improves, but the device complexity and component count increase
Solution Approach 1:
The patent extracts and eliminates the need for separate image reject mixers and additional filtering stages by adopting direct conversion architecture. In direct conversion, the local oscillator frequency is set equal to the intermediate frequency, causing the image frequency to coincide with the desired signal frequency. This naturally eliminates the image rejection problem that plagues superheterodyne architectures, removing the need for complex image reject circuits and associated components.
Solution Approach 2:
Instead of using traditional superheterodyne frequency conversion where the image frequency falls outside the desired band requiring additional rejection, the patent inverts the approach by using direct conversion where the image frequency is deliberately placed at the same frequency as the desired signal. This inversion of the frequency conversion strategy eliminates the image rejection problem by making the image indistinguishable from the desired signal, thereby removing the need for additional image reject components.
Data Source
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.