RF Switch Circuit Diode Biasing for Higher Power Durability
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Solution Overview
Problem
Switch circuits in high-frequency band wireless communications equipment face issues with low power durability, leading to reduced transmitting power, lowered signal switching accuracy, and compromised protection functions, particularly when high-power signals are involved, due to complex circuit configurations and enlarged scales.
Innovation Solution
A switch circuit design incorporating field-effect transistors, control voltage applying terminals, isolation resistors, and diodes in parallel, which improves power durability in the OFF side by maintaining control voltage stability even under high power conditions through specific resistor and diode configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching elements are connected in multiple stages to improve power durability, then power durability is improved, but the scale of the circuit is enlarged and the circuit configuration is complicated
Solution Approach 1:
A diode is introduced as an intermediary component connected in parallel with the gate resistor. This diode acts as a mediator that provides a low-impedance path for RF power signals, preventing them from coupling into the gate of the switching element. By adding this single intermediary component rather than multiple switching stages, the patent achieves improved power durability while avoiding circuit enlargement and complexity increases.
2Power
If high power is inputted in the terminal P3 of the switch SW, then transmitting signals are inputted in the receiver J1 via the terminals P1 and P2 in the OFF side of the switch SW, but the transmitting power is lowered and the protecting function of the receiver J1 by the switch SW is lowered
Solution Approach 1:
The patent converts the harmful high-power RF signals that would otherwise couple into the gate and degrade performance into a beneficial configuration where the diode deliberately provides a preferred path for these signals. The harmful leakage is transformed into a controlled current path through the diode, protecting the gate while maintaining high transmitting power capability and receiver protection function.
3Reliability
If a switch having an improved power durability by connecting switching elements in multiple stages is used, then power durability is improved, but the scale of the circuit is enlarged
Solution Approach 1:
The patent extracts the essential function of improving power durability from the complex multi-stage switching element configuration and implements it through a single, simple diode component connected in parallel with the gate resistor. This extraction approach isolates the power durability enhancement function into a separate, minimal component, achieving the reliability improvement without enlarging the overall circuit scale.
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 design enhances power durability by maintaining control voltage stability, thereby improving the switch circuit's performance in high-power scenarios without increasing circuit complexity, as demonstrated by improved power durability from 43 dBm to 44.5 dBm in comparative examples.
Implementation Method 1
first and second diodes connected in parallel with the first and second resistors respectively and having cathodes connected to the first control voltage applying terminal
Data Source
AI summary
A switch circuit includes: first, second, and third input-output terminals; a first switching element connected between the first and second input-output terminals; a second switching element connected between the third input-output terminal and a grounding point; a third switching element connected between the first and third input-output terminals; a fourth switching element connected between the second input-output terminal and the grounding point; a first control voltage applying terminal connected to control terminals of the first and second switching elements; a second control voltage applying terminal connected to control terminals of the third and fourth switching elements; first and second resistors connected between the control terminals of the first and second switching elements and the first control voltage applying terminal, respectively; and first and second diodes connected in parallel with the first and second resistors, respectively, and having cathodes connected to the first control voltage applying terminal.