RF Switch Branch Impedance Ratio for 5G Isolation
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Solution Overview
Problem
Current radio frequency switch circuitry fails to provide a high off-state to on-state impedance ratio while maintaining maximum isolation in the off-state and minimal insertion loss in the on-state, especially at millimeter wavelength frequencies, which is crucial for 5G wireless networks.
Innovation Solution
The proposed radio frequency switch system incorporates a switch branch with an isolation inductor in parallel and series capacitors to enhance the off-state to on-state impedance ratio, along with a switch controller that applies control signals without digital signal decoding, optimizing impedance and isolation across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radio frequency switch circuitry is used, then the device complexity is low, but the off-state to on-state impedance ratio is insufficient and isolation is not maximum
Solution Approach 1:
The switch branch is divided into multiple segments including switch circuitry, isolation inductor, and series capacitors. Each segment performs a specific function: the switch circuitry provides on/off control, the isolation inductor enhances off-state impedance, and the series capacitors further improve the off-state to on-state impedance ratio. This segmentation allows each component to be optimized independently while working together to achieve maximum isolation.
Solution Approach 2:
An isolation inductor is introduced as an intermediary element between the switch branch terminals. This inductor acts as a mediator that enhances the off-state impedance without significantly affecting the on-state performance. The inductor provides additional isolation by presenting high impedance in the off-state while having minimal impact on signal passage in the on-state.
2Reliability
If switch branches are designed for high off-state impedance, then isolation improves, but insertion loss in the on-state increases
Solution Approach 1:
The impedance characteristics of the switch branch are dynamically changed based on the control signal state. In the on-state, the switch circuitry presents low impedance to minimize insertion loss. In the off-state, the combination of the isolation inductor and series capacitors creates high impedance to maximize isolation. The parameter changes are achieved through the control signal that switches the transistors between conductive and non-conductive states, thereby changing the overall impedance of the branch.
3Productivity
If millimeter wavelength frequency bands are used for 5G networks, then wireless capacity increases, but the requirement for high impedance ratio becomes more challenging
Solution Approach 1:
The switch branch employs a composite structure combining different circuit elements (switch circuitry, inductor, capacitors) that work together to achieve the required impedance characteristics at millimeter wavelengths. This composite approach allows the system to leverage the frequency-dependent properties of each component to maintain high impedance ratio in the challenging millimeter wavelength range used by 5G networks.
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 configuration achieves a minimum off-state to on-state impedance ratio of 35, significantly improving isolation and maintaining low insertion loss, meeting the demands of 5G wireless standards.
Implementation Method 1
isolation inductor in parallel and series capacitors to enhance the off-state to on-state impedance ratio
Data Source
AI summary
A radio frequency switch system includes a plurality of radio frequency switch circuitries that each include a switch branch coupled between a first branch terminal and a second branch terminal and are configured to allow passage of a radio frequency signal through the switch branch in an on-state and to block the radio frequency signal from passing through the switch branch in an off-state in response to a control signal applied to a branch control terminal of the switch branch. Also included is a switch controller configured to apply the control signal to the branch control terminal of the switch branch of each of the plurality of radio frequency switch circuitries, wherein the control signal has a first voltage level that places the switch branch in the on-state and a second voltage level that places the switch branch in the off-state without digital signal decoding of the control signal.