RF Switch Gate Resistor Bypass for Faster Switching and Isolation
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Solution Overview
Problem
Conventional RF switches face challenges in reducing switching and settling times without degrading isolation performance or increasing losses.
Innovation Solution
A switch assembly comprising a first plurality of transistors with a common resistor and a second switch configured to bypass the resistor during transitions, allowing for faster switching times while maintaining isolation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional approaches are used to reduce switching/settling times, then switching speed is improved, but isolation performance degrades and losses increase
Solution Approach 1:
The patent applies dynamics by making the resistance value dynamic rather than static. A switchable resistor is introduced that can change its resistance value based on the operating state. During switching transitions, the resistor provides low resistance to enable fast charging/discharging of gate capacitance. During steady-state operation, the resistor provides high resistance to maintain isolation performance, thus resolving the contradiction between switching speed and isolation.
Solution Approach 2:
The patent changes the resistance parameter dynamically to resolve the contradiction. By using a switchable resistor that alternates between low resistance (during switching) and high resistance (during isolation), the system achieves both fast switching times and maintained isolation performance. This parameter change allows the same circuit element to serve dual purposes at different times.
2Speed
If conventional approaches are used to reduce switching/settling times, then switching speed is improved, but losses in the switch increase
Solution Approach 1:
The dynamic resistance value allows the circuit to optimize for different operational phases. During switching transitions, low resistance minimizes energy loss while enabling fast switching. During steady-state operation, high resistance prevents energy loss by maintaining proper isolation. This dynamic adaptation resolves the contradiction between switching speed and energy loss.
Solution Approach 2:
The switchable resistor operates periodically, alternating between low-resistance mode during switching events and high-resistance mode during isolation periods. This periodic action ensures that energy losses are minimized both during switching (by enabling fast transitions) and during isolation (by maintaining high impedance), thus resolving the contradiction with switching losses.
Data Source
AI summary
A switch assembly for a radio frequency signal and corresponding radio frequency module and wireless device is disclosed. An example switch assembly comprises a first node coupled to an input of the switch assembly, a second node coupled to an output of the switch assembly, a first control node, and a common node; a first switch having a first plurality of transistors coupled between the first and second nodes, each transistor of the first plurality of transistors having a gate, a drain, and a source, each gate of the first plurality of transistors being coupled to the common node; a common resistor coupled between the first control node and the common node; and a second switch coupled between the first control node and the common node in parallel to the common resistor, the second switch configured to selectively bypass the common resistor.