Phase Shifter Bias Line Structure for RF Leakage Isolation
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Solution Overview
Problem
Conventional phase shifters suffer from radio frequency signal leakage towards the bias line, leading to poor bias isolation.
Innovation Solution
The phase shifter design incorporates a bias line with a second wire having greater sheet resistance than the radio frequency transmission line, forming an integrated structure with a narrower line width and a lapping region where the second wire covers the first wire, enhancing the choke effect and reducing signal leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bias line structure is used, then the manufacturing process is simple, but radio frequency signal leakage occurs and bias isolation deteriorates
Solution Approach 1:
The bias line is segmented into multiple conductive layers (first conductive layer and second conductive layer) with different sheet resistances. The first conductive layer has lower sheet resistance for current carrying, while the second conductive layer has higher sheet resistance to block RF signals. This segmentation allows the bias line to simultaneously provide DC bias current while isolating RF signals, resolving the contradiction between simple structure and good bias isolation.
Solution Approach 2:
The bias line employs a composite structure combining two different conductive materials or material configurations with distinct electrical properties. The first conductive layer uses a material with low sheet resistance optimized for DC current flow, while the second conductive layer uses a material with high sheet resistance optimized for RF signal blocking. This composite approach enables the single bias line to perform dual functions without requiring separate structures.
2Reliability
If the line width of the bias line is reduced to improve isolation, then signal leakage decreases, but manufacturing precision requirements increase
Solution Approach 1:
Instead of relying solely on reducing line width (which increases manufacturing precision requirements), the invention changes the fundamental parameter of sheet resistance by using different conductive layers. The second conductive layer's high sheet resistance provides RF signal blocking capability independent of line width, allowing the use of standard manufacturing tolerances while achieving excellent isolation performance.
3Reliability
If a complex multi-layer bias line structure is implemented, then bias isolation improves, but manufacturing cost increases
Solution Approach 1:
The invention merges the DC current carrying function and the RF signal blocking function into a single integrated bias line structure. The first and second conductive layers are formed as part of the same fabrication process sequence, sharing common substrate preparation and patterning steps. This merging approach achieves superior bias isolation without requiring separate independent structures, thereby controlling manufacturing cost.
Solution Approach 2:
The bias line structure is designed to perform multiple functions simultaneously: providing DC bias current through the first conductive layer, blocking RF signals through the second conductive layer, and maintaining electrical connection to the phase shifter device. This multi-functionality eliminates the need for separate structures for each function, reducing overall manufacturing complexity and cost while achieving excellent bias isolation.
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 improved bias isolation, with reductions in signal leakage to below -50 dB, ensuring reliable and stable electrical connections while minimizing manufacturing costs.
Implementation Method 1
A sheet resistance of the second wire is configured to be greater than a sheet resistance of the radio frequency transmission line
Data Source
AI summary
A phase shifter and a wireless communication device are provided. The phase shifter includes a first substrate, a radio frequency transmission line arranged on a side of the first substrate, and a bias line connected to the radio frequency transmission line. The bias line includes a first wire and a second wire. A sheet resistance of the second wire is greater than a sheet resistance of the radio frequency transmission line. The first wire and the radio frequency transmission line are connected and form an integrated structure. A line width of the first wire is less than a line width of the radio frequency transmission line. The second wire and the first wire form a lapping region in an extension direction of the first wire. In the lapping region, the second wire is arranged on a side of the first wire away from the first substrate.