Antenna Tuning Circuit Using Switched Positive Feedback
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Solution Overview
Problem
Existing radio wave receiving apparatuses face challenges in automatically adjusting tuning circuits without a precise oscillation circuit, as they require either a transmission radio wave for tuning or a separate oscillation circuit, which complicates integration and increases component count.
Innovation Solution
A radio wave receiving apparatus with a variable tuning member, a feedback circuit for positive feedback, and a switching member to control feedback operations, allowing for automatic tuning of the antenna frequency without an accurate oscillation circuit, using a simple circuit configuration that includes capacitive elements and switching elements to adjust capacitance and amplify feedback signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate oscillation circuit is provided for tuning processing, then accurate frequency tuning can be achieved, but device complexity and component count increase
Solution Approach 1:
The amplifier circuit is designed to perform multiple functions: it amplifies received radio wave signals during normal reception, and generates oscillation signals during automatic tuning processing. By switching between these modes, the patent eliminates the need for a separate oscillation circuit while maintaining accurate frequency tuning capability
Solution Approach 2:
The patent combines the oscillation circuit functionality with the existing amplifier circuit. The amplifier circuit is configured to operate in two modes: signal amplification mode during reception and oscillation generation mode during tuning, thereby merging two previously separate functions into a single circuit
2Measurement precision
If actual transmission radio wave is used for tuning processing, then accurate frequency adjustment can be performed, but the system cannot tune if transmission radio wave is not available
Solution Approach 1:
The patent introduces a switching circuit as an intermediary that enables the system to switch between two tuning modes: using actual transmission radio waves when available, and using self-generated oscillation signals when transmission radio waves are not available. This intermediary switching mechanism ensures continuous tuning capability under all conditions
3Measurement precision
If a crystal oscillator is used for accurate oscillation frequency, then precise tuning can be achieved, but integration on single chip becomes difficult
Solution Approach 1:
The patent replaces the mechanical crystal oscillator with an electronic oscillation circuit implemented entirely in semiconductor form. The oscillation is generated through electronic feedback mechanisms within the amplifier circuit, eliminating the need for discrete crystal components and enabling full integration on a single chip
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 automatic tuning of the antenna frequency by oscillating at a frequency close to the intended frequency, reducing the need for external oscillation circuits and minimizing the number of components required, while allowing normal reception operations when feedback is turned off.
Implementation Method 1
a positive feedback member to perform a positive feedback in a signal path including the tuning member
Data Source
AI summary
Disclosed is a radio wave receiving apparatus including: an antenna to receive a radio wave; a tuning member to allow a reception frequency of the antenna to be tuned to an intended frequency, in which tuning member a frequency characteristic is variable; a receiving member to receive a reception signal from the antenna to demodulate a modulation wave; a positive feedback member to perform a positive feedback in a signal path including the tuning member; and a switching member to turn on/off a feedback operation of the positive feedback member.