RF Switch Stack Charge Redistribution for OFF-State Leakage
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Solution Overview
Problem
Existing RF switch stacks experience undesired leakage currents during the OFF state, which alter the desired DC voltage distribution, leading to reduced power handling capability and increased design complexity due to the need for larger power supplies to handle these currents.
Innovation Solution
Implementing a charge redistribution resistive ladder and bridge networks to selectively couple and decouple tapping points with transistor terminals, redistributing charges to counteract the effects of leakage currents, thereby maintaining desired voltage distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a stacked configuration of FET transistors is used to handle large RF power, then the power handling capability is improved, but leakage currents are generated during the OFF state that alter DC voltage distribution
Solution Approach 1:
The patent extracts and removes the harmful leakage currents from the system by providing separate body biasing paths for each transistor in the stack. By independently controlling the body voltage of each transistor through dedicated body biasing circuits, the leakage currents that would otherwise flow through the shared body resistive ladder are prevented, thus eliminating the source of DC voltage distribution alteration while maintaining the high power handling capability of the stacked configuration.
Solution Approach 2:
The patent segments the body biasing control for each transistor in the stack, providing independent body biasing circuits rather than using a shared body resistive ladder. This segmentation allows each transistor's body voltage to be independently controlled, preventing the coupling of leakage currents between transistors and maintaining proper DC voltage distribution across the stack while preserving RF power handling capability.
2Device complexity
If body resistive ladders are used to bias the body terminals, then the device complexity is reduced, but the DC voltage distribution is altered by leakage currents
Solution Approach 1:
The patent introduces separate body biasing circuits as intermediary elements between the control logic and the transistor body terminals. These intermediary circuits provide dedicated current paths for biasing each transistor's body, preventing leakage currents from interfering with the DC voltage distribution. This approach maintains relatively simple device complexity while ensuring stable DC voltage distribution by isolating the biasing function from the signal path.
3Reliability
If larger power supplies are used to handle leakage currents, then the reliability is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent converts the harmful effect of leakage currents into a beneficial control mechanism by using separate body biasing circuits. Instead of allowing leakage currents to flow uncontrollably through shared resistive ladders and requiring oversized power supplies, the invention uses the body biasing circuits to actively control and manage the body voltages, preventing harmful leakage while consuming minimal power. This approach improves reliability without increasing power supply requirements or 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 solution effectively reduces the impact of leakage currents on DC voltage distribution, enhancing power handling capability and reducing the need for larger power supplies, thus improving the efficiency and performance of RF switch stacks.
Implementation Method 1
Implementing a charge redistribution resistive ladder and bridge networks to selectively couple and decouple tapping points with transistor terminals, redistributing charges to counteract the effects of leakage currents
Implementation Method 2
a charge redistribution resistive ladder comprising series-connected charge redistribution resistors
Data Source
AI summary
Methods and devices to address body leakage current generation and bias voltage distribution associated with body leakage current in an OFF state of a FET switch stack are disclosed. The devices include charge redistribution arrangements and bridge networks to perform coupling/decoupling to/from the FET switch stack. Detailed structures of such bridge networks are also described.