SSDL Circulator Segmented Delay Lines Wideband Isolation
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Solution Overview
Problem
Traditional circulators, both ferrite-based and active, face limitations in wideband performance, size compatibility with integrated circuits, and high noise, making them unsuitable for modern communication and radar systems requiring high performance and reciprocity.
Innovation Solution
The implementation of a Sequentially-Switched Delay Line (SSDL) circulator, which uses time-switching strategies to achieve non-reciprocity by sequentially turning on and off switches connected to multiple delay lines, enabling true passive circulators with high isolation across a wide frequency range, suitable for on-chip integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional ferrite-based circulators are used, then non-reciprocal signal separation is achieved, but the device size is large and wideband performance is limited
Solution Approach 1:
The circulator is segmented into multiple delay line segments (first, second, third delay lines) with different delay values, allowing the system to achieve wideband performance through sequential switching of segments rather than requiring a single large ferrite cavity structure
Solution Approach 2:
The circulator employs dynamic switching between different delay line segments using switches controlled by control signals, enabling the device to adapt its characteristics across different frequency bands and time periods, replacing the static ferrite cavity approach
2Area of stationary object
If active circulators based on transistors are used, then small physical size and IC compatibility are achieved, but high noise and limited power performance occur
Solution Approach 1:
The control signals for switching between delay line segments are derived from the input signal itself through processing (e.g., using the input signal to control switches in sequence), making the system self-regulating and eliminating the need for external active control circuits that would introduce noise
Solution Approach 2:
The patent replaces active electronic switching components (transistors) with passive switching mechanisms controlled by signal timing, substituting active electronic control with a passive time-domain switching approach that avoids active device noise
3Adaptability or versatility
If parametric modulation architecture is applied to resonant ring, then non-reciprocity at RF is achieved, but high insertion loss and extremely narrow isolation bandwidth occur
Solution Approach 1:
The circulator uses periodic switching of delay line segments in sequence, where each segment is activated for a specific time period corresponding to its delay value, creating a periodic time-varying transmission path that achieves wide isolation bandwidth without the narrow bandwidth limitations of resonant ring approaches
Solution Approach 2:
The system changes the transmission path parameters (delay values) by switching between different delay line segments, allowing the circulator to maintain low insertion loss across a wide frequency range by adapting the delay characteristics to match the input signal frequency
4Adaptability or versatility
If Time-Varying Transmission Line (TVTL) technology is used, then broadband isolation is achieved, but large chip area is required for low RF frequencies
Solution Approach 1:
The transmission line is segmented into multiple discrete delay line segments with different delay values, allowing the system to achieve broadband operation by switching between segments rather than requiring a single long transmission line that would occupy large chip area
Solution Approach 2:
Multiple delay line segments serve multiple functions: each segment provides a specific delay value for different frequency ranges, and through sequential switching, the same physical structure achieves operation across a wide frequency spectrum from low RF to microwave frequencies without requiring proportionally large chip area
Data Source
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AI summary
A passive circulator utilizing sequentially-switched delay lines (SSDL) in which delay line sections are sequentially turned on and off to achieve non-reciprocity to provide rejection/separations between different signals at the same/similar frequency, such as between a transmitted and received signal. The circulator is well-suited for on-chip integration and can be utilized across a wide frequency range. Various embodiments are described for separating signal waveforms.