RF Switch Branch Isolation Inductor Resonance
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Solution Overview
Problem
Radio frequency switch circuitry fails to provide sufficient isolation between signal ports at millimeter wavelength frequencies, leading to impractically low off-state to on-state impedance ratios, which is inadequate for meeting the demands of 5G wireless standards.
Innovation Solution
Incorporating an isolation inductor in parallel with the switch branch to provide resonance with the total off-state capacitance, enhancing the off-state to on-state impedance ratio while maintaining minimal insertion loss in the on-state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radio frequency switch circuitry is used at millimeter wavelength frequencies, then the basic switching function is maintained, but the isolation between signal ports deteriorates and the off-state to on-state impedance ratio becomes impractically low
Solution Approach 1:
An isolation inductor is introduced as an intermediary component coupled between the series-coupled switch branches. This inductor provides additional isolation between signal ports at millimeter wavelength frequencies by creating a resonant circuit with the off-state capacitance of the switch branches, thereby improving port isolation without compromising the impedance ratio
Solution Approach 2:
The patent modifies the electrical parameters of the switch circuitry by selecting specific inductance values for the isolation inductor that resonate with the off-state capacitance at the operating frequency. This parameter optimization enables achieving both high isolation and maintained impedance ratio simultaneously at millimeter wavelength frequencies
2Reliability
If switch branches are designed for high isolation in off-state, then port isolation improves, but insertion loss increases in on-state
Solution Approach 1:
The patent optimizes the inductance value of the isolation inductor to create a resonant frequency that matches the operating frequency. This careful parameter selection ensures that the inductor provides maximum isolation in the off-state while having minimal impact on signal transmission in the on-state, thereby maintaining low 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
The solution achieves a significant increase in isolation between signal ports, with an off-state to on-state impedance ratio of at least 35, effectively meeting the 5G performance specifications and ensuring maximum isolation with minimal insertion loss.
Implementation Method 1
the isolation inductor has a given inductance that provides resonance with a total off-state capacitance of the switch branch in the off-state at a center frequency of the radio frequency signal
Data Source
AI summary
Disclosed is radio frequency switch circuitry that includes a switch branch having a first branch terminal coupled to a first signal port and a second branch terminal coupled to a second signal port, and a branch control terminal, wherein the switch branch has both an on-state and an off-state to control passage of a radio frequency signal between the first signal port and the second signal port in response to a control signal applied to the control terminal. The radio frequency switch circuitry further includes an isolation inductor coupled between the first branch terminal and the second branch terminal such that the isolation inductor is in parallel with the switch branch, wherein the isolation inductor has a given inductance that provides resonance with a total off-state capacitance of the switch branch in the off-state at a center frequency of the radio frequency signal.