Direct-Conversion Video Receiver for Low-Power Image Rejection
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Solution Overview
Problem
Existing silicon tuners for analog video reception face challenges in achieving a balance between image rejection and power consumption, leading to compromised performance at low power or high power consumption, making them unsuitable for small portable devices.
Innovation Solution
An integrated analog video receiver with a direct-conversion tuner that converts broadcast-frequency signals directly to baseband, incorporating offset cancellation circuitry and adaptive image rejection to improve performance while reducing power consumption, and a power management system to power down components during superfluous video intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete tuner cans with analog components are used, then image rejection performance is improved, but power consumption increases to two to three watts
Solution Approach 1:
The patent replaces the mechanical/analog discrete component tuner can with a silicon-based integrated circuit implementation. This substitution integrates multiple functions (tuning, demodulation, image rejection) into a single chip, dramatically reducing power consumption from 2-3 watts to under 100 microwatts while maintaining image rejection performance through integrated signal processing pathways.
Solution Approach 2:
The patent merges multiple discrete components (tuner, demodulator, image rejection filters) into a single integrated silicon tuner can. This consolidation integrates the local oscillator, mixer, and filtering functions into one chip, reducing overall power consumption and enabling portable applications while preserving the necessary image rejection capabilities through integrated design.
2Use of energy by moving object
If silicon tuners with superheterodyne architecture are used, then power consumption is reduced, but image rejection performance deteriorates due to poor integrated passive performance
Solution Approach 1:
The patent segments the signal processing functions into distinct integrated blocks within the silicon chip: a direct-conversion mixer stage, a separate IQ imbalance correction block, and dedicated digital signal processing. This segmentation allows each function to be optimized independently, achieving both low power consumption and effective image rejection through coordinated operation of the separated functional blocks.
Solution Approach 2:
The patent employs parameter changes by implementing adaptive IQ imbalance correction that dynamically adjusts correction parameters based on measured signal characteristics. This allows the integrated silicon tuner to compensate for manufacturing variations in passive components, maintaining image rejection performance despite the inherent limitations of integrated passives while keeping power consumption low.
3Volume of moving object
If direct-conversion architecture is used, then device size and power consumption are reduced, but offset cancellation complexity increases
Solution Approach 1:
The patent replaces complex analog offset cancellation circuitry with digital signal processing techniques implemented in the silicon tuner. By using digital algorithms to detect and cancel offsets after the mixing stage, the design achieves compact size while managing complexity through software-based solutions rather than additional analog components.
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
The solution enables efficient image rejection with reduced power consumption, making the analog video receiver suitable for small portable devices by minimizing power usage and maintaining performance.
Implementation Method 1
a direct-conversion tuner that converts broadcast-frequency signals directly to baseband
Data Source
AI summary
An integrated circuit device having a television signal tuner, video decoder and power control circuit. The television signal tuner selects one of a plurality of television channels, and the video decoder converts a television signal conveyed in the selected television channel into a video display signal. The power control circuit alternately enables and disables the television tuner to enable reception of a first portion of video information conveyed in the television signal and to disable reception of a second portion of the video information.