Multiband Front-End Switch Control for Signal Isolation and Low Loss
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Solution Overview
Problem
Existing front-end circuits for communication devices experience signal loss across different frequency bands due to the resistance characteristics of switches used to isolate and connect filters, leading to inefficiencies in signal transmission and reception.
Innovation Solution
A front-end circuit design that employs a switch with adjustable resistance states by applying control signals to modify the voltage thresholds, ensuring higher resistance in non-conductive states to prevent signal leakage and lower resistance in conductive states to minimize signal loss, using MOSFETs or bipolar transistors with back gate voltages or base currents for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resistance of the switch when being non-conductive is low, then it is easier to connect the filter path, but signals leak from the first frequency band path to the second frequency band path causing signal loss
Solution Approach 1:
The patent applies dynamics by making the switch resistance variable rather than fixed. The switch resistance is dynamically adjusted based on the operational state: set to a high value (first resistance) when isolating frequency bands to prevent signal leakage, and set to a low value (second resistance) when connecting active frequency bands to minimize signal loss. This dynamic adaptation resolves the contradiction between isolation reliability and signal loss.
Solution Approach 2:
The patent changes the resistance parameter of the switch according to different operational requirements. By controlling the switch resistance to be higher than a threshold when non-conductive and lower than another threshold when conductive, the system optimizes both signal isolation and transmission efficiency. This parameter adjustment directly addresses the technical contradiction by adapting the electrical characteristics to the operational state.
2Reliability
If the resistance of the switch when being conductive is high, then signal leakage is reduced, but there is a loss in the signal of the used frequency band
Solution Approach 1:
The switch resistance is dynamically controlled to provide different resistance values for isolation and conduction states. When the switch is non-conductive, high resistance ensures signal isolation; when conductive, low resistance maximizes signal transmission efficiency. This dynamic behavior resolves the contradiction between isolation reliability and transmission productivity.
Solution Approach 2:
The resistance parameter of the switch is changed based on the operational state. The control mechanism ensures that the switch presents a high resistance value when isolating frequency bands and a low resistance value when conducting signals, thereby optimizing both isolation and transmission performance according to the system's needs.
3Adaptability or versatility
If multiple filters are connected in common at their input/output terminals, then multiband capability is achieved, but signal leakage between frequency bands occurs
Solution Approach 1:
The patent applies dynamics by implementing variable resistance switches that adapt their resistance values based on the active frequency band. When a frequency band is not in use, the corresponding switch is set to high resistance to isolate that band's filter, preventing signal leakage. When a frequency band is active, its switch is set to low resistance to minimize signal loss. This dynamic control enables multiband capability while preventing signal leakage.
Solution Approach 2:
The resistance parameter of each switch in the filter paths is changed according to the operational state of corresponding frequency bands. By adjusting the resistance values to be appropriately high for inactive bands and low for active bands, the system achieves multiband capability while minimizing signal loss and preventing interference between bands.
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 effectively reduces or prevents signal loss across frequency bands, enhancing communication efficiency by ensuring minimal signal leakage and optimal signal transmission when switching between frequency bands.
Implementation Method 1
the first switch receives a first control signal, a second control signal or both, the first control signal is a signal to increase a difference between a first voltage and a threshold voltage, the first voltage being applied to the first switch to turn the first switch to a non-conductive state, the threshold voltage determining whether the first switch is turned to a conductive state or not
Data Source
AI summary
A front-end circuit includes a first filter on a path connecting a common terminal and a first input/output terminal, a second filter on a path connecting the common terminal and a second input/output terminal, and a first switch on the path connecting the common terminal and the first input/output terminal. The first switch receives at least one of a first control signal and a second control signal. The first control signal increases a difference between a first voltage applied to the first switch to turn the first switch to a non-conductive state and a threshold voltage determining whether or not the first switch is turned to a conductive state. The second control signal increases a difference between a second voltage applied to the first switch to turn the first switch to the conductive state and the threshold voltage.