Direct-Conversion Digital Receiver with Integrated Tuner Functions
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Solution Overview
Problem
Traditional digital receivers require separate tuner and digital receiver circuitry, leading to increased cost and circuit area due to the need for image rejection and channel selection, especially when processing analog and digital signals simultaneously.
Innovation Solution
Integration of tuner functions in a digital receiver using a direct down-conversion circuit with mixers, low pass filters, and a local oscillator circuit, which includes quadrature components for down-conversion and subsequent processing through analog-to-digital and digital-to-analog converters, allowing for efficient conversion and demodulation of RF signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate tuner and digital receiver circuitry are used, then image rejection and channel selection are maintained, but circuit area and cost increase
Solution Approach 1:
The patent combines the tuner circuitry and digital receiver circuitry into a single integrated circuit. The tuner down-converts the RF signal to an intermediate frequency, and the digital receiver processes this signal digitally. By integrating these previously separate functions into one chip, the patent reduces the overall circuit area while maintaining the necessary image rejection and channel selection capabilities through coordinated analog-digital processing.
2Adaptability or versatility
If separate tuner and digital receiver circuitry are used, then signal processing functions are maintained, but manufacturing cost increases
Solution Approach 1:
The patent integrates multiple signal processing functions (tuning, down-conversion, demodulation, and digital processing) into a single hybrid analog-digital receiver circuit. This consolidation reduces the number of discrete components needed, simplifies the bill of materials, and lowers manufacturing costs through economies of scale and reduced assembly complexity, while preserving full signal processing capability.
Solution Approach 2:
The integrated circuit is designed to handle multiple signal processing functions within a single device. The tuner can select and down-convert different channels, and the digital receiver can process various modulation types, making the integrated circuit universally capable of receiving and processing different television signals without requiring separate specialized circuits for each function.
3Reliability
If analog and digital signals are processed separately, then signal integrity is maintained, but circuit complexity increases
Solution Approach 1:
The patent introduces an intermediate frequency (IF) stage as a mediator between the analog tuner and the digital receiver. The tuner down-converts the RF signal to an IF signal, which is then processed by the digital receiver after analog-to-digital conversion. This intermediate stage allows the analog and digital portions to interact in a controlled manner, maintaining signal integrity by providing a stable transition point while reducing overall circuit complexity compared to direct digital conversion of high-frequency RF signals.
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 integration reduces the need for separate circuitry, minimizing circuit area and cost while maintaining effective image rejection and channel selection, enabling efficient processing of both analog and digital signals.
Implementation Method 1
The direct down conversion circuit provides a downconverted signal based on the RF input signal and a local oscillator (LO) signal
Implementation Method 2
a low pass filter coupled to the output of the mixers
Implementation Method 3
The first and second downconverted quadrature components are multiplexed and passed through at least one analog-to-digital converter to provide a digital signal
Implementation Method 4
At least one digital-to-analog converter (DAC) receives a digital representation of the local oscillator signal from the local oscillator circuit and converts the digital representation into an analog local oscillator signal
Implementation Method 5
A narrow band filter provides the local oscillator signal to the direct down conversion circuit
Data Source
AI summary
A receiver to process a RF input signal having a plurality of channels includes a direct down conversion circuit, a demodulation circuit, and a local oscillator circuit. The direct down conversion circuit provides a downconverted signal based on the RF input signal and a local oscillator signal. The demodulation circuit receives the downconverted signal and provides a demodulated signal. The local oscillator circuit sets a frequency of the local oscillator signal based on a selected channel of the plurality of channels.