Switch Module Capacitive Impedance Insertion Loss
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Solution Overview
Problem
Existing switch modules that switch between signal paths based on frequency bands face challenges in reducing insertion loss due to the tradeoff between capacitance and resistance in series-connected switches, which affects impedance matching and signal leakage.
Innovation Solution
A switch module design that includes first and second filters with specific frequency bands and switches configured to maintain capacitive impedance, preventing the impedance from being in a short state, thereby reducing insertion loss without the need for shunt-connected switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the capacitance of a series-connected switch that is turned OFF is decreased to reduce signal leakage, then the resistance of this series-connected switch when turned ON increases, thereby increasing the insertion loss
Solution Approach 1:
An impedance transformation circuit is introduced as an intermediary component between the series-connected switch and the signal path. This circuit transforms the capacitive impedance of the OFF state switch into a high impedance, effectively reducing signal leakage without requiring the switch capacitance to be minimized. Consequently, the switch can be designed with larger capacitance for better OFF state isolation while maintaining low insertion loss in the ON state through proper impedance transformation.
2Object-generated harmful factors
If shunt-connected switches are added to connect signal paths and ground points to reduce signal leakage, then the device complexity increases
Solution Approach 1:
The shunt-connected switches that connect signal paths to ground points are extracted and removed from the system. Instead, an impedance transformation circuit is employed to achieve the same signal leakage reduction function by transforming the impedance of the series-connected switch, thereby simplifying the overall device structure while maintaining effective isolation.
Solution Approach 2:
The impedance transformation circuit serves multiple functions simultaneously: it transforms the capacitive impedance of the OFF state switch to high impedance for signal leakage reduction, and it also matches the impedance for the ON state to minimize insertion loss. This multi-functionality eliminates the need for separate shunt-connected switches, reducing device complexity.
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 design effectively reduces insertion loss by maintaining an open-state impedance, minimizing signal leakage and improving isolation characteristics, even when the pass bands of filters overlap.
Implementation Method 1
Impedance of the first filter for a signal in the second frequency band is capacitive
Implementation Method 2
When the first switch is turned OFF, impedance of the first switch is capacitive
Implementation Method 3
The second filter is configured to pass a signal in a third frequency band. The third frequency band is included in the second frequency band
Data Source
AI summary
A switch module includes a first terminal, first and second filters, and first and second switches. Impedance of the first filter for a signal in a stop band is capacitive. When the first switch is turned OFF, impedance of the first switch is capacitive, and impedance of the first filter seen from an end portion of the first switch connected to the first filter is not in a short state and impedance of the first filter seen from the first terminal is in an open state.