Bootstrapped Self-Biasing Shunt Switch for RF Linearity Trade-Offs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Shunt switches for radio frequency, microwave, and mm-wave circuits face a trade-off between linearity and on-state resistance, with more transistors improving linearity but degrading resistance, and fewer transistors improving resistance but degrading linearity.
Innovation Solution
A self-biasing shunt switch with bootstrapping, comprising a transistor stack, a capacitor, and a bootstrapping transistor, which transitions to an on or off state based on signal power thresholds, using bias sources and resistors to control gate and source voltages, allowing for improved linearity and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a larger number of transistors are used in the shunt switch, then linearity is improved, but on-state resistance degrades
Solution Approach 1:
The shunt switch is divided into multiple transistor stages (first transistor, second transistor, third transistor) connected in series. Each transistor contributes to the overall switching function while distributing the voltage and current stress, enabling better linearity through the stacked configuration without proportionally increasing on-state resistance loss.
Solution Approach 2:
The patent introduces a bootstrapping transistor connected in a feedback configuration that operates in a different control dimension. This bootstrapping mechanism dynamically adjusts the gate voltages of the transistors in the stack, adding a new degree of freedom for controlling switch performance that independently optimizes both linearity and on-state resistance.
2Object-affected harmful factors
If a smaller number of transistors are used in the shunt switch, then on-state resistance is improved, but linearity degrades
Solution Approach 1:
The bootstrapping transistor creates a dynamic biasing system where gate voltages are continuously adjusted based on the switching state and signal conditions. This dynamic control allows the transistors to operate in optimal regions throughout the signal cycle, maintaining low on-state resistance while preserving linearity through adaptive voltage regulation.
Solution Approach 2:
The bootstrapping transistor is connected in a feedback configuration that monitors the switching state and automatically adjusts the gate voltages of the transistor stack. This feedback mechanism ensures that the switch maintains optimal performance characteristics, compensating for non-linear effects and resistance variations in real-time during operation.
Data Source
AI summary
A shunt switch. In some embodiments, the shunt switch includes a transistor stack including a first transistor and a capacitor. The transistor stack may have a first end terminal and a second end terminal, the first transistor being connected to the first end terminal, the first end terminal being connected to a switching terminal of the shunt switch. The capacitor may have a first terminal connected to the second end terminal of the transistor stack, and a second terminal connected to a low-impedance node.