Monolithic Bootstrap Circuit Integration in Power Transistors
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Solution Overview
Problem
The challenge lies in achieving complete silicon-level integration of bootstrap circuit elements, such as semiconductor-based bootstrap capacitors and diodes, with power transistors and other circuitry to reduce space and costs while providing simplified solutions, as existing approaches often require separate modules and face limitations in integrating these components effectively.
Innovation Solution
The integration of semiconductor-based bootstrap capacitors and transistors monolithically with power transistors within a single package, using techniques like trench formation and lateral MOSFET technologies, allows for a system-on-silicon configuration, reducing area requirements and parasitic effects, and simplifying assembly and design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bootstrap circuits are provided separately in addition to the package housing the power transistor, then the bootstrap circuit can function effectively with sufficient space and components, but the overall device area and complexity increase
Solution Approach 1:
The patent integrates the bootstrap circuit elements (capacitor and diode) directly into the power transistor device structure. The capacitor is formed within the semiconductor substrate using doped regions, and the diode is integrated using the same substrate, allowing both bootstrap components to coexist with the power transistor in a single compact package, thereby reducing overall device area while maintaining functionality
Solution Approach 2:
The bootstrap circuit elements are nested within the power transistor device structure. The capacitor is embedded in the semiconductor substrate, and the diode is formed using the same substrate regions, creating a hierarchical integration where smaller components are contained within the larger power transistor package, maximizing space utilization
2Adaptability or versatility
If system-in-package configurations are used with bootstrap circuit module, then the bootstrap circuit can be provided along with other modules in a single package, but the bootstrap circuit remains at least partially distinct and integration complexity increases
Solution Approach 1:
The patent merges the bootstrap circuit elements with the power transistor at the semiconductor fabrication level. The capacitor is formed using doped regions in the substrate, and the diode is created using the same substrate material and processing steps, resulting in a unified device structure rather than separate modules, thereby reducing integration complexity
Solution Approach 2:
The semiconductor substrate serves multiple functions: it acts as the base for the power transistor, the capacitor dielectric, and the diode structure. This multi-functionality allows a single substrate to fulfill multiple circuit roles, simplifying the overall device architecture and reducing the number of separate components needed
3Ease of manufacture
If complete silicon-level integration of bootstrap circuit elements is achieved, then space and costs are reduced with simplified solutions, but the range of bootstrap capacitances needed creates integration challenges
Solution Approach 1:
The patent enables dynamic adjustment of capacitance values by allowing selective connection of different capacitor configurations. The integrated structure permits switching between different capacitor plates or series/parallel combinations, providing a range of capacitance values from a single integrated device, thereby maintaining manufacturing simplicity while achieving adaptability
Solution Approach 2:
The capacitor is divided into multiple selectable sections or plates that can be independently connected or disconnected. This segmentation allows the circuit to achieve different capacitance values by activating only the required portions, providing a range of capacitances while maintaining a compact integrated structure
Data Source
AI summary
Embodiments relate to bootstrap circuits integrated with at least one other device, such as a power transistor or other semiconductor device. In embodiments, the bootstrap circuit can comprise a bootstrap capacitor and a bootstrap diode, or the bootstrap circuit can comprise a bootstrap capacitor and a bootstrap transistor. The bootstrap capacitor comprises a semiconductor-based capacitor, as opposed to an electrolytic, ceramic or other capacitor, in embodiments. The integration of the bootstrap circuit with another circuit or device, such as a power transistor device in one embodiment, is at a silicon-level in embodiments, rather than as a module-like system-in-package of conventional approaches. In other words, the combination of the bootstrap circuit elements and power transistor or other device forms a system-on-silicon, or an integrated circuit, in embodiments, and additionally can be arranged in a single package.