RF Switch Stack Charge Redistribution for Leakage Bias Stability
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Solution Overview
Problem
In RF switch stacks, undesired leakage currents alter the desired DC voltage distribution, leading to reduced power handling capability and increased design costs due to the need for larger power supplies to handle these currents.
Innovation Solution
Implement a charge redistribution resistive ladder with tapping points and bridge networks to selectively couple or decouple these points with transistor terminals, redistributing charges to counteract the de-biasing effect of leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large RF voltage is applied to the antenna, then the RF power handling requirement is met, but undesired leakage currents are generated that alter the DC voltage distribution
Solution Approach 1:
A charge redistribution circuit is introduced as an intermediary component between the RF switch stack and ground. This circuit includes a capacitor coupled to a first node in the RF switch stack and a resistor connecting the capacitor to ground. The intermediary circuit redistributes charge accumulated during RF operation to counteract leakage currents, thereby maintaining stable DC voltage distribution while enabling large RF voltage operation.
2Strength
If the FET switch stack is designed to block large RF voltages, then power handling capability is improved, but the de-biasing effect of leakage currents reduces the effectiveness of voltage blocking
Solution Approach 1:
The charge redistribution circuit operates as a feedback mechanism that continuously monitors and corrects DC voltage distribution in the RF switch stack. During RF operation, leakage currents cause voltage shifts that are detected through the capacitor-resistor network, which then redistributes charge to counteract these shifts, maintaining the intended DC bias conditions and ensuring reliable voltage blocking capability.
3Reliability
If larger power supplies are used to handle leakage currents, then the DC voltage distribution stability is maintained, but device complexity and cost increase
Solution Approach 1:
The charge redistribution circuit enables the RF switch stack to self-correct its own DC voltage distribution issues. Rather than requiring larger external power supplies to force current through leakage paths, the capacitor-resistor network autonomously redistributes charge within the existing power supply rails, allowing the system to maintain stable DC bias conditions using standard power supply components.
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 approach maintains desired DC voltage distribution, enhancing power handling capability and reducing the need for larger power supplies, thus optimizing switch stack performance and cost.
Implementation Method 1
Implement a charge redistribution resistive ladder with tapping points and bridge networks to selectively couple or decouple these points with transistor terminals, redistributing charges to counteract the de-biasing effect of leakage currents
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.