Dual-Conversion TV Tuner With BAW Filtering for Adjacent Channel Rejection
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Solution Overview
Problem
Current digital terrestrial television receivers face challenges in accurately discriminating desired channels from adjacent channels and noise, due to significant power differences and stringent signal/noise ratio requirements, which pose constraints on filter design and integration.
Innovation Solution
An integrated electronic component utilizing a bulk acoustic wave filter, baseband filter, and digital filter, along with a multibit analog/digital conversion stage and phase/amplitude correction, to effectively filter out adjacent channels and correct errors, with in-situ determination of the central frequency of the bulk acoustic wave filter to enhance channel selection and noise rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional filtering methods are used to reject adjacent channels, then channel selection capability is improved, but device complexity and integration difficulty increase significantly
Solution Approach 1:
The filtering function is segmented into multiple stages: a first filtering stage for initial adjacent channel rejection, followed by a second filtering stage for further refinement. This segmentation allows each stage to handle a portion of the total rejection requirement, reducing the complexity burden on any single filter while achieving the cumulative 40 dB rejection target.
Solution Approach 2:
A frequency transposition stage is introduced as an intermediary between the receiving antenna and the filtering stages. This intermediary performs frequency conversion to shift the desired channel to a different frequency position, enabling the subsequent filters to more effectively separate the desired channel from adjacent channels in the frequency domain, thereby simplifying the filter design.
2Reliability
If high rejection levels are implemented to meet signal/noise ratio requirements, then signal quality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The total 40 dB rejection requirement is segmented across multiple filtering stages rather than requiring a single high-precision filter to achieve the entire rejection level. Each filtering stage operates with more relaxed precision requirements, and their combined effect achieves the overall signal/noise ratio target, thereby reducing individual manufacturing precision constraints.
Solution Approach 2:
The filtering system is designed to provide rejection capability that exceeds the minimum requirement at each stage. By implementing partial rejection at the first filtering stage and additional rejection at the second filtering stage, the system ensures the cumulative effect meets the 40 dB target while allowing each individual stage to operate within achievable manufacturing precision limits.
3Measurement precision
If multiple filtering stages are used to achieve 40 dB adjacent channel rejection, then channel discrimination capability is improved, but device integration becomes more difficult
Solution Approach 1:
Multiple filtering stages and the frequency transposition stage are merged into a single integrated circuit device. By combining these previously separate components into one monolithic integration, the patent reduces the practical integration difficulties associated with coordinating multiple discrete filters and frequency converters, while maintaining the enhanced channel discrimination capability provided by the multi-stage filtering approach.
Solution Approach 2:
The integrated device performs multiple functions within a single unit: frequency transposition, initial filtering, additional filtering, and signal output. This multi-functionality consolidates what would otherwise require separate components, simplifying the overall system integration while achieving the required 40 dB adjacent channel rejection and improved channel discrimination.
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
Enables efficient rejection of adjacent channels and improved signal quality by combining filters and multibit conversion, allowing for a fully integrated receiver solution that meets the stringent requirements of digital terrestrial television.
Implementation Method 1
a bandpass filter of the bulk acoustic wave type disposed between the two frequency transposition stages of the tuning module
Data Source
AI summary
An integrated circuit includes a dual-conversion tuner, firstly upconverting so as to place a signal outside the reception band, then downconverting with zero intermediate frequency. A bulk acoustic wave type filter is calibrated in such a way as to accurately determine its central frequency. This filter is positioned between the two frequency transposition stages of the tuner. After baseband filtering, the signals are digitized then processed in a digital block BNM which includes a channel decoding module.