Balanced Bridge for RF Signal Separation
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Solution Overview
Problem
Traditional vector network analyzers (VNAs) are bulky, expensive, and unreliable due to the need for multiple directional couplers and receivers, which also limit their bandwidth and increase complexity.
Innovation Solution
A balanced bridge system using a differential signal source and equal-ratio resistive dividers to separate forward and reverse signals, eliminating the need for directional couplers by canceling common modes with a resistive bridge structure, and employing differential receivers to achieve wide bandwidth and high directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional directional couplers and multiple receivers are used in VNA test set, then measurement functionality is achieved, but device complexity and physical size increase significantly
Solution Approach 1:
The patent combines multiple directional coupler functions into a single resistive bridge structure. The bridge integrates the functionality of separating forward and reverse signals that would traditionally require multiple couplers, thereby reducing device complexity while maintaining measurement precision through the balanced bridge configuration
Solution Approach 2:
The resistive bridge structure serves multiple functions simultaneously: it acts as a directional coupler, a signal separator, and a balance network. This multi-functional design eliminates the need for separate directional couplers and reduces the number of receivers needed, directly addressing the complexity issue
2Adaptability or versatility
If multiple mechanical switches and couplers are used in traditional VNA, then signal routing is achieved, but reliability decreases due to frequent switching
Solution Approach 1:
The patent replaces mechanical switches and couplers with an electrical resistive bridge system. The signal routing and separation functions previously achieved through mechanical switching are now accomplished through electrical connections and resistive voltage division, eliminating wear and reliability issues associated with mechanical components
3Adaptability or versatility
If conventional balun with magnetic components is used, then broadband operation is achieved, but device size and cost increase
Solution Approach 1:
The patent extracts and eliminates magnetic components (ferrite beads, magnetic cores) from the broadband matching network. The broadband operation previously achieved through magnetic components is now accomplished through a purely resistive bridge configuration, significantly reducing device size while maintaining wide bandwidth from DC to high frequencies
Solution Approach 2:
The patent changes the fundamental parameters of the broadband matching approach by transitioning from magnetic material-based solutions to resistive voltage division. This parameter change enables broadband operation without the size and cost penalties of magnetic components
4Adaptability or versatility
If traditional VNA architecture with multiple ports and receivers is used, then comprehensive measurement capability is achieved, but cost and physical footprint increase
Solution Approach 1:
The patent merges multiple receiver functions into a single receiver by using the resistive bridge to pre-separate forward and reverse signals. This consolidation maintains comprehensive measurement capability while dramatically reducing the physical footprint and cost associated with multiple receivers and their supporting infrastructure
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 provides a compact, cost-effective, and reliable VNA with wide bandwidth from DC to high frequencies, minimizing physical size and complexity while maintaining high directivity and isolating incoming and outgoing signals effectively.
Implementation Method 1
at least one equal-ratio resistive divider wherein one side of the resistive divider is attached to the first output, and the second side of the resistive divider is connected to the second output and the middle point of the resistive divider is connected to a receiver
Implementation Method 2
employing differential receivers to achieve wide bandwidth and high directivity
Data Source
AI summary
A directional bridge for characterizing a signal reflected from an RF device under test (DUT) the bridge comprising: a differential signal source with two antipodal outputs wherein the first output is connected to a reference termination, and the second output is connected to the DUT, and at least one equal-ratio resistive divider wherein one side of the resistive divider is attached to the first output, and the second side of the resistive divider is connected to the second output and the middle point of the resistive divider is connected to a receiver, wherein the at least one equal-ratio resistive divider is configured to provide a separated forward and reverse signals by canceling a differential mode of a transmitted signal at the bridge.