Bootstrapped Switch Circuit for Fast Static-Bias Switching
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Solution Overview
Problem
Conventional bootstrapped switches with complex designs struggle to achieve fast ON/OFF switching speeds when operating with static bias voltages, which is a requirement for high-speed applications.
Innovation Solution
A simplified bootstrapped switch design that includes a first transistor, a capacitor, a first voltage providing circuit, and a second voltage providing circuit, where the first voltage providing circuit switches between ground and supply voltage during ON and OFF periods, and the second voltage providing circuit applies a boost voltage during the OFF period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If device sizes are increased to reduce MOS on-resistance, then switching speed is improved, but parasitic capacitance increases
Solution Approach 1:
The patent changes the voltage parameter applied to the gate terminal by using a bootstrapping mechanism that dynamically adjusts the gate voltage based on the input signal level. This allows the switch to achieve low on-resistance without requiring oversized transistors, thereby maintaining fast switching speed while minimizing parasitic capacitance.
2Reliability
If conventional bootstrapped switch design is used to minimize MOS switch on-resistance variation, then distortion is reduced, but gate voltage exceeds supply voltage causing reliability issues
Solution Approach 1:
The patent introduces an intermediary mechanism using a capacitor coupled to the gate terminal that stores and releases charge to maintain the bootstrapping effect. This intermediary approach allows the gate voltage to be dynamically controlled without directly exceeding the supply voltage, thereby maintaining reliability while reducing distortion.
3Reliability
If conventional bootstrapped switch with complex design is used, then bootstrapping function is achieved, but switching speed is limited by MOS resistance and parasitic capacitance
Solution Approach 1:
The patent extracts the essential bootstrapping function from the complex conventional design by using a simplified circuit configuration. The key element is a capacitor connected to the gate terminal that provides the necessary voltage boosting without requiring the complex multi-transistor architecture of conventional designs, thereby achieving fast switching speed while maintaining the bootstrapping function.
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 simplified design achieves fast ON/OFF switching speeds by optimizing charge redistribution and reducing the reliance on low on-resistance MOS transistors, thereby enhancing switching speed and reducing chip area and power consumption.
Implementation Method 1
The capacitor has a first end and a second end, wherein the first end is coupled to the control terminal of the first transistor
Data Source
AI summary
A bootstrapped switch includes a first transistor, a capacitor, a first voltage providing circuit, and a second voltage providing circuit. Regarding the first transistor, a first connection terminal receives a static bias voltage, and a second connection terminal generates an output voltage. A first end of the capacitor is coupled to a control terminal of the first transistor. The first voltage providing circuit provides a first voltage to a second end of the capacitor during a first period in which the first transistor is turned off, and provides a second voltage to the second end of the capacitor during a second period in which the first transistor is turned on. The second voltage providing circuit provides a boost voltage to the control terminal of the first transistor during the first period, and stops providing the boost voltage to the control terminal of the first transistor during the second period.