Tapped Transmission Line for Compact RF Signal Distribution
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Solution Overview
Problem
Current solutions for signal distribution and aggregation in radio-frequency circuits, such as power splitters and directional couplers, are not suitable for integration into circuits and face challenges like space consumption and signal loss, particularly at high frequencies.
Innovation Solution
The use of a transmission-line medium with substantially identical tap element amplifiers at regular intervals, forming an artificial transmission line with reduced characteristic impedance and cut-off frequency above the desired signal range, along with methods to compensate for transmission-line medium losses, such as tapered impedance and negative resistance circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power splitters/combiners are used for signal distribution, then signal can be distributed to multiple transceivers, but the device consumes space and requires amplifiers to compensate for loss
Solution Approach 1:
The patent replaces traditional mechanical power splitters and directional couplers with an artificial transmission line implemented using distributed RC circuits on an integrated circuit substrate. This substitution eliminates the need for bulky discrete components while maintaining signal distribution functionality through electrical field propagation along the transmission line.
Solution Approach 2:
The patent changes the characteristic impedance parameter of the transmission line by distributing resistive and capacitive elements along the line. By carefully selecting the resistance and capacitance values of the distributed elements, the characteristic impedance is transformed to match the impedance of connected transceivers, enabling direct connection without additional matching networks.
2Adaptability or versatility
If directional couplers are used for signal distribution, then broadband matching can be maintained, but the device requires ferrite transformers and consumes space on the order of 1/4-wavelength
Solution Approach 1:
The patent replaces ferrite transformer-based directional couplers with an integrated artificial transmission line using RC circuits. This eliminates the need for ferrite materials and large-scale electromagnetic structures, enabling broadband signal distribution in a compact integrated circuit format.
Solution Approach 2:
The patent introduces distributed resistive and capacitive elements as intermediary components along the transmission line. These elements serve as impedance transformation mediators, gradually transforming the characteristic impedance along the line to achieve broadband matching without requiring discrete transformer components.
3Area of stationary object
If transmission-line medium is used for signal distribution, then compact integration is achieved, but transmission-line medium losses occur due to resistivity
Solution Approach 1:
The patent changes the electrical parameters of the transmission line by distributing resistive and capacitive elements. The resistive elements are designed with specific values that, while causing some loss, are compensated for by the impedance transformation effect. The capacitive elements extend the frequency response, allowing the system to operate effectively at higher frequencies where transmission line losses are typically more significant.
Solution Approach 2:
The patent applies different resistance and capacitance values at different locations along the transmission line. The distributed elements are not uniform but are strategically designed with varying parameters to optimize signal distribution to multiple taps while minimizing overall loss and maintaining impedance matching at each connection point.
4Ease of operation
If tap element amplifiers are used for signal distribution, then signal can be distributed to multiple points, but device complexity increases
Solution Approach 1:
The patent extracts the amplification function from discrete amplifier components and integrates it directly into the transmission line structure itself. The distributed RC elements provide both impedance transformation and signal distribution functions, eliminating the need for separate amplifier stages at each tap point.
Solution Approach 2:
The artificial transmission line serves multiple functions simultaneously: it provides signal distribution to multiple taps, performs impedance transformation, and maintains broadband matching. This multi-functionality is achieved through the distributed RC circuit structure, which combines what would traditionally require separate components into a single integrated 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
Enables compact, power-efficient signal distribution and aggregation in RFICs, supporting frequencies exceeding 80 GHz, with reduced signal loss and instability, suitable for smart-antenna and MIMO systems.
Implementation Method 1
each amplifier having a predominantly capacitive input impedance. The short transmission-line medium sections between tap elements, combined with the tap element amplifier input capacitance, form an artificial transmission-line medium of reduced characteristic impedance
Implementation Method 2
Another related embodiment compensates for transmission-line medium loss by attaching negative-resistance-producing circuits along the transmission-line medium
Data Source
AI summary
A tapped transmission line for distributing an electrical signal, such as an RF signal, to multiple modules, and/or aggregating signals from multiple modules. Embodiments of the invention provide a tapped transmission line based on a transmission-line medium along which tap elements are dispersed, so that the tap elements have a predominantly capacitive loading of the transmission-line medium. Methods for compensating the loss of the transmission-line medium are presented as well. Applications for distribution of transmitted signals, of local oscillator signals, and to aggregation of signals from multiple oscillators are disclosed. The invention is particularly applicable to integrated circuits (IC, ASIC, RFIC), and to multichannel RF systems such as phased array and MIMO systems.