Parallel RF Switch Stacks With Capacitor Balancing for Fast Settling
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Solution Overview
Problem
Conventional RF switches with large FET stacks suffer from slow settling times and non-uniform RF voltage distribution, leading to low power handling capability and high off-state leakage currents.
Innovation Solution
Implementing RF switches with parallel transistor stacks and capacitor networks to balance RF voltages, allowing for faster switching and reduced leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large FET stacks are used to achieve higher power handling capability, then power handling capability is improved, but settling time becomes relatively slow
Solution Approach 1:
The patent divides a single large FET stack into multiple smaller FET stacks connected in parallel. Each smaller stack has reduced gate capacitance and faster switching characteristics, while the parallel configuration maintains the overall power handling capability. This segmentation resolves the contradiction by achieving fast settling time through smaller individual units while preserving high power handling through parallel arrangement.
2Power
If large FET stacks are used to achieve higher power handling capability, then power handling capability is improved, but non-uniform RF voltage distribution results in low power handling capability
Solution Approach 1:
The patent segments the power handling function across multiple parallel FET stacks, where each stack handles a portion of the total power. This segmentation, combined with individual balancing capacitors for each stack, enables uniform RF voltage distribution across all stacks while maintaining high overall power handling capability.
Solution Approach 2:
The patent introduces balancing capacitors as intermediary elements connected to each FET stack. These capacitors actively balance the RF voltage distribution across parallel stacks, preventing non-uniform voltage patterns that would limit power handling capability. The balancing capacitors mediate between the parallel stacks to achieve uniform voltage distribution.
3Stability of the object's composition
If conventional techniques are used for balancing RF voltage distribution, then RF voltage distribution is balanced, but leakage currents become undesirably high
Solution Approach 1:
The patent applies local quality by placing individual balancing capacitors at each FET stack location rather than using a conventional centralized balancing technique. This localized approach allows each stack to be independently balanced, achieving uniform RF voltage distribution while minimizing leakage currents through optimized local capacitance values tailored to each stack's characteristics.
Data Source
AI summary
A switch circuit includes first and second transistor stacks coupled in parallel between first and second ports. The first transistor stack includes a first plurality of transistors coupled in series between the first and second ports to provide a first variably-conductive path between the first and second ports. A first network of one or more balancing capacitors includes a first capacitor coupled across multiple transistors of the first plurality of transistors. The second transistor stack includes a second plurality of transistors coupled in series between the first and second ports to provide a second variably-conductive path between the first and second ports. A second network of one or more balancing capacitors includes a second capacitor coupled across multiple transistors of the second plurality of transistors.