Antenna Switching Circuit Ground Path Layout for RF Isolation
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Solution Overview
Problem
Existing antenna switch semiconductor integrated circuits face challenges in maintaining isolation characteristics due to parasitic capacitances in switches, leading to radio frequency signal leakage and increased circuit scale.
Innovation Solution
A switching circuit with a reduced circuit scale is designed, incorporating a ground switch connected to one of the input-output terminals through multiple switches, and specific path switches are controlled to ensure that the input-output terminals are isolated from each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple shunt switches are used to suppress radio frequency signal leakage and improve isolation characteristics, then isolation characteristics are improved, but circuit scale increases
Solution Approach 1:
The patent extracts the essential ground-switching function from multiple shunt switches and concentrates it into a single ground switch. By removing the redundant switching elements while maintaining the ground connection capability, the circuit achieves the same isolation effect with reduced complexity. The single ground switch connects to a node that is strategically positioned to provide effective grounding for suppressing radio frequency signal leakage without requiring multiple separate shunt switches.
2Adaptability or versatility
If switches are used to control conduction paths, then conduction path switching is enabled, but parasitic capacitances cause radio frequency signal leakage
Solution Approach 1:
The patent introduces an intermediary grounding mechanism that mediates between the switching elements and the radio frequency signals. The ground switch acts as an intermediary that provides a controlled path to ground, allowing the switching elements to change conduction paths while the intermediary grounding suppresses the harmful radio frequency leakage that would otherwise occur through the parasitic capacitances of the switches.
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 proposed solution effectively suppresses radio frequency signal leakage and maintains sufficient isolation characteristics between input-output terminals, while reducing the circuit scale and preventing degradation of isolation.
Implementation Method 1
The switches have parasitic capacitances, and thus part of a radio frequency signal may be conducted even in non-conducting states
Data Source
AI summary
A switching circuit includes a first antenna terminal and a second antenna terminal, a first input-output terminal and a second input-output terminal, a plurality of switches and a ground switch. When an electrical connection destination of the first input-output terminal is switched to the first antenna terminal, a first path switch included in the plurality of switches and provided along a first path connecting the first input-output terminal and the first antenna terminal to each other, and a second path switch and the ground switch provided along a second path connecting the second input-output terminal and the ground to each other, the second path switch included in the plurality of switches, are in conducting states, and a third path switch included in the plurality of switches and provided along a third path connecting the first path and the second path to each other is in a non-conducting state.