FET RF Switch Stack Charge Redistribution for OFF-State Leakage
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Solution Overview
Problem
In RF switch stacks, undesired leakage currents during the OFF state alter the desired DC voltage distribution, leading to reduced power handling capability and increased design costs due to the need for additional circuitry to manage these currents.
Innovation Solution
The implementation of a charge redistribution resistive ladder with tapping points and bridge networks that selectively couple/decouple these points with the drain/source and body terminals of FET transistors, redistributing charges to counteract the de-biasing effect and maintain optimal voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a FET switch stack 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 and reduce performance
Solution Approach 1:
The patent extracts the harmful leakage current effect by introducing a separate charge redistribution network that independently manages charge distribution. The network includes resistors connected between drain/source and body terminals that actively redistribute charges to counteract the leakage currents, separating the power handling function from the charge management function.
Solution Approach 2:
The patent introduces a charge redistribution network as an intermediary system between the RF signal path and the DC bias network. This network includes resistors and tapping points that mediate the charge distribution, preventing leakage currents from directly affecting the DC voltage distribution while allowing the FET stack to continue handling large RF power.
2Stability of the object's composition
If additional circuitry is added to manage leakage currents and maintain DC voltage distribution, then the voltage distribution stability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the charge redistribution function with the existing FET switch stack structure by utilizing the same physical components (drain, source, and body terminals) for dual purposes. The charge redistribution network is integrated into the stack architecture, combining power handling and charge management in a unified structure rather than adding completely separate circuits.
Solution Approach 2:
The FET switch stack components serve multiple functions: the drain and source terminals handle both RF power switching and charge redistribution, while the body terminal participates in both device operation and charge management. The resistors in the charge redistribution network are connected to existing terminals, making those terminals universal interfaces for both power handling and voltage stabilization.
3Strength
If the gate voltage is made more negative relative to drain/source voltage to increase blocking capability, then the voltage blocking capability is improved, but the leakage currents increase due to altered DC voltage distribution
Solution Approach 1:
The patent applies a counteracting mechanism where the charge redistribution network generates opposing currents to balance the harmful leakage currents. The resistors connected between drain/source and body terminals create a charge redistribution effect that counterweights the leakage current-induced voltage shifts, allowing the gate voltage to be optimized for blocking capability without the penalty of increased leakage.
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 solution effectively reduces the de-biasing effect, enhancing the power handling capability of the transistors while minimizing the need for additional circuitry, thus reducing design costs and improving overall system performance.
Implementation Method 1
a charge redistribution resistive ladder with tapping points and bridge networks that selectively couple/decouple these points with the drain/source and body terminals of FET transistors, redistributing charges to counteract the de-biasing effect
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.