DTV Analog Front End With Selectable ADC Clocks
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Solution Overview
Problem
Digital television (DTV) systems face challenges in selectively processing sound intermediate frequency signals and differential DTV and analog TV broadcast signals, requiring an efficient analog front end (AFE) that can handle various sampling frequencies and standards.
Innovation Solution
The proposed solution involves an analog front end (AFE) with a first selection circuit for outputting differential sound or TV broadcast signals and a second selection circuit for outputting clock signals with different sampling frequencies, combined with an analog-to-digital converter to convert these signals into digital codes, utilizing a fractional-N phase locked loop for generating sampling clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple clock signals with different sampling frequencies are used to support various DTV standards, then adaptability to different broadcasting systems is improved, but device complexity increases due to the need for multiple clock signals and selection circuits
Solution Approach 1:
The AFE system is designed to process multiple types of signals (analog TV broadcast signals, DTV broadcast signals, and sound intermediate frequency signals) through a unified architecture. The analog-to-digital converter and selection circuits can handle different signal types by selectively connecting them to the ADC, allowing one system to perform multiple functions without requiring separate processing paths for each signal type.
Solution Approach 2:
The system employs dynamic selection of clock signals based on the input signal type. A selection circuit dynamically chooses the appropriate clock signal from multiple available clock signals with different sampling frequencies, matching the clock signal to the specific DTV standard being processed. This dynamic adaptation allows the system to handle various broadcasting standards without fixed hardware configurations.
2Device complexity
If a unified AFE system processes multiple signal types (analog TV, DTV, sound IF), then device complexity is reduced by consolidating processing paths, but adaptability to different sampling frequencies and standards becomes more difficult to achieve
Solution Approach 1:
The system uses dynamic clock signal selection to adapt to different sampling frequency requirements. A selection circuit receives multiple clock signals with different sampling frequencies and dynamically connects the appropriate clock signal to the analog-to-digital converter based on the input signal type. This allows the unified processing path to adapt to various DTV standards and sampling frequencies without requiring separate dedicated paths for each standard.
Solution Approach 2:
The system changes operational parameters (sampling frequency, clock signal selection) based on the input signal type. By adjusting which clock signal is supplied to the ADC and how the selection circuits are configured, the unified AFE system can process analog TV broadcast signals, DTV broadcast signals, and sound intermediate frequency signals with different sampling requirements through the same hardware path.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables the AFE to selectively process and convert sound and TV broadcast signals across various DTV standards, reducing bandwidth usage and enabling multicasting, while ensuring efficient signal processing and compatibility with different DTV standards.
Implementation Method 1
utilizing a fractional-N phase locked loop for generating sampling clock signals
Data Source
AI summary
Provided is an analog front end of a digital TV, a digital TV system having the same, and a method of operating the same. The analog front end includes: a first selection circuit which selectively outputs differential sound intermediate frequency signals or differential TV broadcast signals in response to a first selection signal; a second selection circuit which outputs a clock signal among a plurality of clock signals having a different sampling frequencies, in response to a second selection signal; and an analog-to-digital converter which converts output signals output from the first selection circuit to a digital code, according to a sampling frequency of a clock signal output from the second selection circuit.