Front-End Tunable Filter Calibration Using a Negative Resistance Oscillator
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Solution Overview
Problem
The existing tuning schemes for communication and broadcast receivers are complex, dependent on the signal reception link, costly, and lack independence, reusability, and portability due to their involvement with multiple modules and extra processing requirements.
Innovation Solution
A tuning calibration circuit using an active device to form a negative resistance oscillator with controllable oscillation frequency and amplitude, allowing for independent adjustment of oscillation signals without requiring the signal reception link, reducing hardware costs and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing tuning schemes are used, then the receiver can be tuned to desired frequencies, but the system complexity increases and the circuit becomes dependent on multiple modules
Solution Approach 1:
The patent separates the tuning calibration function from the signal reception link by dividing the system into independent modules: a dedicated tuning calibration circuit and a signal reception link. This segmentation allows the tuning calibration to be performed independently without affecting or being affected by the signal reception process, thereby improving reliability while managing complexity through modular design.
Solution Approach 2:
The patent extracts the tuning calibration function from the signal reception link and places it in a separate tuning calibration circuit. This extraction eliminates the dependency between tuning calibration and signal reception, allowing the tuning calibration circuit to operate independently and improving system reliability without requiring multiple interconnected modules.
2Adaptability or versatility
If existing tuning schemes are used, then frequency tuning can be achieved, but additional hardware costs and processing requirements increase
Solution Approach 1:
The patent designs the tuning calibration circuit with universal applicability to various receiver topologies (zero-IF, low-IF, high-IF, multi-IF). The circuit uses standard components and a unified design approach that can be adapted to different receiver architectures without requiring topology-specific modifications, thereby improving adaptability while avoiding additional hardware complexity.
Solution Approach 2:
The patent employs a simplified tuning calibration circuit that replicates the essential tuning function without copying the complex signal reception processing chain. By using a dedicated voltage-controlled oscillator and simple feedback mechanism instead of full signal processing paths, the design achieves versatility across receiver types while minimizing hardware requirements and processing needs.
3Ease of operation
If signal reception link is used for tuning calibration, then tuning can be performed, but power consumption increases and tuning speed decreases
Solution Approach 1:
The patent performs tuning calibration as a preliminary action before signal reception begins. The dedicated tuning calibration circuit prepares the system by establishing the correct operating frequency and conditions in advance, allowing the main signal reception process to proceed efficiently without requiring additional power-intensive calibration operations during normal operation. This preliminary tuning action reduces overall power consumption while maintaining ease of operation.
Solution Approach 2:
The patent implements a self-service tuning calibration mechanism where the voltage-controlled oscillator automatically adjusts its frequency based on feedback from a frequency discriminator and control voltage generator. This self-regulating system eliminates the need for external intervention or complex control logic during tuning, reducing power consumption while maintaining ease of operation through automatic frequency locking.
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 solution enables faster tuning, reduced power consumption, and increased independence, reusability, and portability of the tuning calibration circuit, making it suitable for various receiver topologies while minimizing additional circuitry and processing needs.
Implementation Method 1
The active device and the pre-filter may form a negative resistance oscillator when the receiver needs to tune the pre-filter
Data Source
AI summary
A circuit for a front-end tunable filter of a communication and broadcast receiver and a tuning method thereof are described herein. In one aspect, the circuit of the tunable filter may be independent of the signal reception link of the receiver. The pre-filter (104) includes a variable capacitance (146) which is adjusted by a tuning signal (160). A negative resistance element (144) and the pre-filter (104) may form an oscillator. The negative resistance element (144) is controlled by an amplitude control signal (162) outputted from an oscillation amplitude control circuit (142). The oscillation amplitude control circuit (142) stabilizes the amplitude of a radio frequency signal (130) in a preset range. An oscillation frequency control circuit (140) stabilizes the frequency of the signal (130) in a preset frequency range by a tuning signal (160). The tuning is completed until both of the amplitude and the frequency of the oscillation signal meet the preset ranges.