Switchable Ground-Plane TTD Phase Shifter With Low Insertion Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing true time-delay (TDD) phase shifters using switched transmission lines face high insertion loss and limited linearity, particularly in high-frequency applications like millimeter wave bands, due to the nonlinearity of switches and longer transmission lines required for delay, leading to beam squint issues.
Innovation Solution
The implementation of a TDD phase shifter using microstrip transmission lines with switchable ground planes, where the ground planes can be switched between a ground and floating state to provide different delays, reducing insertion loss and achieving infinite linearity by leveraging parasitic capacitance to control signal propagation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switched transmission lines are used to provide time delay, then phase shifting capability is achieved, but insertion loss increases and linearity deteriorates
Solution Approach 1:
The patent extracts the delay functionality from the transmission line itself and implements it through switchable ground planes. The transmission line remains short and fixed, while the ground planes are selectively connected or disconnected to create different delay paths, eliminating the need for long transmission lines and reducing insertion loss.
Solution Approach 2:
The patent introduces switchable ground planes as intermediary elements between the transmission line and ground. These ground planes, when switched, create parasitic capacitance that mediates the delay function without requiring the signal to traverse long transmission lines, thereby maintaining linearity while reducing insertion loss.
2Loss of time
If longer transmission lines are used to provide delay, then time delay increases, but insertion loss increases
Solution Approach 1:
The patent extracts the delay function from the transmission line length and relocates it to the ground plane switching mechanism. The transmission line remains short and fixed, while the delay is achieved by selectively connecting ground planes that create different parasitic capacitance values, thus providing delay without increasing insertion loss.
Solution Approach 2:
The patent changes the electrical parameters of the transmission path by switching ground planes. Instead of changing physical length, the effective electrical delay is adjusted by modifying the parasitic capacitance through ground plane connection states, allowing delay variation without proportional increase in insertion loss.
3Adaptability or versatility
If switches are used to select transmission lines, then phase shifting is achieved, but linearity deteriorates due to switch nonlinearity
Solution Approach 1:
The patent introduces ground planes as intermediary elements that, when switched, create parasitic capacitance to control signal delay. This intermediary mechanism provides the necessary phase shifting capability while the fixed transmission line structure maintains signal integrity and linearity, overcoming the linearity deterioration caused by direct switch placement in the signal path.
4Reliability
If TTD lines are used instead of phase shifters, then beam squint issues are reduced, but device complexity increases
Solution Approach 1:
The patent merges the phase shifter functionality with a compact TTD structure by integrating switchable ground planes directly onto the transmission line substrate. This combination achieves TTD performance with reduced beam squint while avoiding the complexity of separate, long transmission lines, effectively merging the benefits of both approaches in a unified compact structure.
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 approach results in a low-loss, high-linearity TDD phase shifter with reduced die area, capable of providing selectable delays with minimal insertion loss variation between reference and delayed modes, enhancing the performance in phased array systems.
Implementation Method 1
achieving infinite linearity by leveraging parasitic capacitance to control signal propagation speed
Data Source
AI summary
Systems, devices, and methods related to phase shifters are provided. An example true time-delay (TTD) phase shifter structure includes a signal conductive line disposed on a first layer of the structure; a first switchable ground plane comprising a first conductive plane disposed on a second layer of the structure; a second switchable ground plane comprising a second conductive plane disposed on a third layer of the structure, where the first, second, and third layers are separate layers of the structure; a first switch coupled between the first switchable ground plane and a first ground element, the first ground element disposed on the second layer; and a second switch coupled between the second switchable ground plane and a second ground element, the second ground element disposed on the third layer.