Photoconductive High Frequency Switch for mmWave Signal Transmission
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Solution Overview
Problem
Current high-frequency signal transmitting/receiving devices face challenges with bulky components, high parasitic capacitance, and complex bias and supply circuits, leading to RF loss, high power consumption, and cost issues, especially for frequencies above 10 GHz, making integration into compact devices difficult.
Innovation Solution
A high-frequency switch utilizing a photoconductive semiconductor element with conductivity adjusted by control light, integrated into a coplanar waveguide structure with a minimal number of components, providing galvanic isolation and low power consumption, and capable of operating up to 100 GHz with low mmWave loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional switching components (PIN diodes, MOSFETs, MEMS) are used in high-frequency circuits, then switching functionality is achieved, but device complexity and manufacturing cost increase due to complex bias circuits and supply circuits
Solution Approach 1:
The patent replaces conventional electrical switching mechanisms (PIN diodes, MOSFETs, MEMS) with an optically controlled photoconductive switch. This substitution eliminates the need for complex bias circuits and DC supply circuits, as the switching is controlled by optical signals rather than electrical biasing. The photoconductive switch uses light to modulate conductivity, thereby removing the problematic electrical bias infrastructure while maintaining switching functionality at high frequencies.
2Speed
If miniaturization is implemented for high-frequency operation, then operating frequency increases, but RF loss increases due to intersection of RF channels with bias and DC supply circuits
Solution Approach 1:
The patent extracts and removes the bias circuits and DC supply circuits from the high-frequency signal path. By using optical control instead of electrical biasing, the RF channel is decoupled from these parasitic circuits, eliminating the RF loss that occurs when RF channels intersect with bias and supply circuits. This allows miniaturization to proceed without the penalty of increased RF loss from circuit intersections.
3Ease of manufacture
If bulky components are used to avoid integration issues, then manufacturing simplicity is maintained, but device size and PCB area increase
Solution Approach 1:
The patent merges the switching functionality with a compact coplanar waveguide structure. The photoconductive switch is integrated directly into the transmission line, eliminating the need for separate bulky components and their associated mounting hardware. This integration achieves both miniaturization and manufacturing simplicity, as the compact design can be fabricated using standard PCB techniques without requiring large discrete components.
4Ease of operation
If photoconductive switch module with light guiding layer is used, then optical control is achieved, but power consumption increases due to excessive lighting power
Solution Approach 1:
The patent optimizes the photoconductive material properties and optical coupling efficiency to reduce the power required for optical control. By selecting appropriate photoconductive materials with high quantum efficiency and optimizing the geometric configuration for light delivery, the system achieves effective switching with minimal optical power, thereby reducing power consumption while maintaining optical control capability.
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 achieves low losses, low control power, small size, and simple supply/bias circuitry, reducing complexity, size, and manufacturing costs while maintaining high blocking performance and wide frequency range compatibility.
Implementation Method 1
Principle of operation of the optically controlled components is based on the photoconductivity effect, i.e. the ability of a semiconductor material to change its electrical characteristics by switching from a dielectric to conductive state depending on lighting.
Data Source
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AI summary
Disclosed is a high frequency switch including a substrate, a pair of ground sections provided on the substrate, a center conductor provided between the pair of ground sections, and a photoconductive semiconductor element provided on the center conductor and extending between the center conductor and the pair of ground sections.