Active Bootstrap Supply Generator Using Low-Voltage Transistor Stacks
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Solution Overview
Problem
Conventional voltage converters face inefficiencies due to the use of passive diode-based bootstrapping schemes, which may not be feasible in devices lacking high-voltage transistors like HEMTs, and can be costly in discrete power switch configurations.
Innovation Solution
An active bootstrapping scheme using low-voltage transistors integrated on the same IC chip, forming a stack with self-referenced gate and source/drain voltages, or incorporating a high-power n-type transistor and charge pump to generate a boosted voltage for high-side drivers, eliminating the need for high-voltage transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive diode-based bootstrapping schemes are used, then the bootstrapped-supply voltage can be generated, but the operation efficiency of the voltage converter deteriorates
Solution Approach 1:
The patent replaces passive diode-based bootstrapping with an active transistor-based bootstrapping circuit. The active circuit uses transistors (such as high-voltage p-type transistors or complementary transistor pairs) to actively control the charging and discharging of the bootstrap capacitor, substituting the passive diode mechanism with an active switching mechanism that improves efficiency while maintaining manufacturability through standard CMOS or bipolar processes.
Solution Approach 2:
The patent changes the operating parameters of the bootstrapping circuit by using transistors with specific voltage thresholds and gain characteristics. The active transistor circuit can dynamically adjust the voltage levels and current flow during bootstrapping, allowing for optimized efficiency performance while accommodating standard manufacturing processes through careful selection of transistor parameters and circuit topology.
2Loss of energy
If high-voltage transistors are used in alternative bootstrapping schemes, then the bootstrapped-supply voltage can be generated with improved efficiency, but the device complexity increases due to availability constraints
Solution Approach 1:
The patent inverts the conventional approach by using low-voltage transistors (standard CMOS or bipolar transistors available in most devices) instead of requiring high-voltage transistors. The circuit topology is designed such that multiple low-voltage transistors work together to achieve the high-voltage bootstrapping function, making the solution adaptable to devices with standard transistor inventories while maintaining improved efficiency.
Solution Approach 2:
The patent segments the high-voltage bootstrapping function into multiple low-voltage transistor stages. Instead of relying on a single high-voltage transistor, the circuit uses a series or parallel combination of standard low-voltage transistors to progressively build up the required voltage levels, making the solution compatible with devices that have limited or no high-voltage transistor availability.
3Loss of energy
If alternative bootstrapping schemes without diodes are used, then the bootstrapping efficiency is improved, but the cost increases due to additional high-voltage components
Solution Approach 1:
The patent designs the active bootstrapping circuit using standard transistors that serve multiple functions: they act as switches, voltage regulators, and level shifters within the same circuit. This multi-functionality eliminates the need for separate high-voltage components, reducing overall component count and manufacturing cost while maintaining the efficiency benefits of active bootstrapping.
Solution Approach 2:
The patent uses standard low-voltage transistor designs (well-established in semiconductor manufacturing) to create the bootstrapping circuit, rather than requiring specialized high-voltage transistor designs. This allows the use of proven, cost-effective manufacturing processes and readily available transistor models, reducing development and production costs while achieving improved efficiency through the active circuit topology.
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 enhances efficiency and reduces costs by enabling active bootstrap circuits in high-voltage converters without requiring high-voltage transistors, while integrating the solution on a low-voltage IC chip with other components.
Implementation Method 1
a capacitor including a first plate coupled to a third node, a first voltage node coupled to the first plate of the capacitor, and a second voltage node coupled to a second plate of the capacitor
Data Source
AI summary
Some embodiments include an apparatus having a first node to receive a connection from a gate of a first transistor of a voltage converter; a second node to receive a connection from a gate of a second transistor of the voltage converter; a third node to receive a connection from a node between the first and second transistors; a capacitor including a first plate coupled to the third node; a first driver including an output node coupled to the first node, a first voltage node coupled to the first plate of the capacitor, and a second voltage node coupled to a second plate of the capacitor; a second driver including an output node coupled to the second node; and a circuit including third transistors coupled in series between the second voltage node and a third voltage node.