MEMS Phase Shifter Shuttle Capacitor Plate Design
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Solution Overview
Problem
Current broadband RF MEMS phase shifters suffer from high insertion loss, particularly in higher frequency bands, which limits their performance in applications like satellite communications.
Innovation Solution
A MEMS phase shifter design featuring a shuttle with a capacitor plate that moves between two positions, varying capacitance and thus phase length, is implemented. The phase shifter includes a housing, an electrical conductor, and a shuttle with an actuator section, allowing for low-loss operation by adjusting the capacitance between the conductor and ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If MMIC digital phase shifters are used to achieve miniaturization and integration, then device compactness is improved, but insertion loss increases significantly
Solution Approach 1:
The patent replaces conventional MMIC electronic phase shifting mechanisms with a MEMS-based mechanical system. A movable capacitor plate is actuated by a piezoelectric element to change capacitance values, thereby achieving phase shifting through mechanical displacement rather than electronic modulation. This substitution reduces insertion loss while maintaining miniaturization benefits.
Solution Approach 2:
The invention changes the operating parameters by using variable capacitance values achieved through mechanical displacement of the capacitor plate. By adjusting the plate position relative to the fixed electrode, the capacitance changes, which in turn modifies the phase shift without incurring the high losses associated with MMIC digital phase shifters.
2Ease of operation
If conventional phase shifters are used to achieve phase shifting functionality, then phase control is achieved, but power-handling capability is limited
Solution Approach 1:
The patent employs a mechanical MEMS structure with a movable capacitor plate actuated by a piezoelectric element, replacing conventional electronic phase shifters. This mechanical approach enables both precise phase control through capacitance variation and superior power-handling capability, as the mechanical structure can withstand higher power levels without the limitations of solid-state electronic components.
3Adaptability or versatility
If broadband operation is implemented to cover frequency ranges from 300 MHz to 300 GHz, then frequency coverage is improved, but insertion loss increases at higher frequencies
Solution Approach 1:
The invention achieves broadband operation by varying the capacitance parameter through mechanical displacement of the capacitor plate. The MEMS structure maintains low insertion loss across the entire frequency range from 300 MHz to 300 GHz because the capacitive phase shifting mechanism is inherently less lossy than electronic alternatives, particularly at millimeter-wave frequencies where conventional MMIC phase shifters suffer from 7 dB or higher insertion loss.
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 design achieves low insertion loss and high power-handling capability, enabling efficient phase shifting across broad frequency bands, particularly in satellite communications, while being scalable and integratable into various systems.
Implementation Method 1
The plate and said electrical conductor in combination form a capacitor having a capacitance value. This capacitance value will vary depending upon whether said plate is spaced at said first distance as compared to said second distance.
Implementation Method 2
This variance in capacitance advantageously changes a phase length of the transmission line.
Data Source
AI summary
Embodiments of phase shifters (10) include electrical conductors (34) suspended within an electrically-conductive housing (28), and a shuttle (16) having an electrically-conductive plate (74) that provides a variable capacitance between a ground potential and the electrical conductor (34) when the shuttle (16) is moved between a first and second position. The plate (74) is electrically connected to a ground plane (27) of the phase shifter (10) by adjacent electrically-conductive portions (54, 55b, 53a) of the shuttle (16).