Integrated Enhancement-Depletion MOS Composite Device for High-Power Switching
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Solution Overview
Problem
Existing switching power supplies face challenges in balancing startup time and standby power consumption, with prior solutions increasing complexity and cost, and being limited in high-power scenarios.
Innovation Solution
A composite device integrating a first enhancement-mode MOS device and a depletion-mode MOS device, sharing a common high-voltage ring, with an isolator to enhance withstand voltage, allowing for reduced process complexity and cost, and applicability to high-power scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a resistor is used for high-voltage startup and power supply, then the startup process can be completed, but there is a tradeoff between startup time and standby power consumption
Solution Approach 1:
The patent segments the power supply function into two distinct devices: an enhancement-mode MOS device for startup current supply and a depletion-mode MOS device for standby power supply. This segmentation allows each device to be optimized for its specific function, resolving the contradiction between startup time and standby power consumption by eliminating the need for a resistor that must compromise between these two parameters.
Solution Approach 2:
The patent changes the operational parameters of the MOS devices by applying different gate-source voltages. The enhancement-mode device operates in enhancement mode during startup, while the depletion-mode device operates in depletion mode during standby. This parameter change enables the system to achieve fast startup without high standby power consumption, as each mode is optimized for its respective operational phase.
2Reliability
If separate enhancement-mode and depletion-mode MOS devices are used, then startup and standby functions can be optimized, but device complexity and cost increase
Solution Approach 1:
The patent merges the enhancement-mode MOS device and depletion-mode MOS device into a single integrated composite device structure. Both devices share common components including the epitaxial region, high-voltage ring, and back-side drain electrode. This merging reduces device complexity and manufacturing cost while maintaining the functional optimization of having separate enhancement and depletion mode devices for different operational phases.
Solution Approach 2:
The composite device structure serves multiple functions: it provides both enhancement-mode operation for startup and depletion-mode operation for standby, while also sharing common structural elements to reduce complexity. The single integrated structure performs the functions of what would traditionally require separate discrete devices, achieving universality that resolves the contradiction between functional optimization and device complexity.
3Device complexity
If high-voltage devices are integrated, then process complexity is reduced, but withstand voltage between devices may be insufficient
Solution Approach 1:
The patent applies local quality by creating an isolator structure with different doping characteristics in specific regions between the enhancement-mode and depletion-mode devices. The isolator includes a first region with first doping characteristics and a second region with second doping characteristics, providing localized electrical isolation where needed while maintaining overall device integration. This local quality approach ensures sufficient withstand voltage between devices without requiring complex isolation processes throughout the entire structure.
Solution Approach 2:
The isolator structure functions as a composite region combining different doped materials to achieve both integration and isolation. By复合ing regions with different doping characteristics (first doping characteristics and second doping characteristics) in specific locations, the patent creates a composite structure that provides the necessary electrical isolation for high-voltage withstand while maintaining process simplicity and device integration.
Data Source
AI summary
This invention provides a composite device and a switching power supply. The composite device integrates therein a first enhancement-mode MOS device and a depletion-mode MOS device, and comprises: an epitaxial region of a first doping type; a first well region and a second well region formed in parallel on the front side of the epitaxial region; a first doped region of the first doping type formed within the first well region; a gate of the first enhancement-mode MOS device; a second doped region of the first doping type formed within the second well region; a channel region of the first doping type, wherein the channel region extends from a boundary of the second well region to a boundary of the second doped region; and a gate of the depletion-mode MOS device. The switching power supply includes the composite device above. This invention can decrease the process complexity, reduce the chip area and cost, and may be applicable to high power scenarios.