Cascode Diode Circuit With Ultralow Forward Voltage at Lower Cost
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Solution Overview
Problem
High power and high performance circuit applications require cost-effective solutions that balance performance and cost, as high voltage SiC transistors used in cascode diode circuits are expensive, making them challenging for commercial use.
Innovation Solution
A cascode diode circuit comprising a normally on transistor, a low voltage diode, and a high voltage diode, where the normally on transistor has a gate, drain, and source, with the low voltage diode connected to the source and gate, and the high voltage diode connected between the normally on transistor and low voltage diode, offering a cost-effective alternative with ultralow forward voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage SiC transistors are used in cascode diode circuits, then high efficiency and high voltage operation are achieved, but cost increases significantly
Solution Approach 1:
The invention segments the cascode diode circuit into three distinct components: a normally-on high voltage transistor, a low voltage diode, and a high voltage diode. This segmentation allows each component to be optimized independently for its specific function, enabling the use of cheaper materials and manufacturing processes for the low voltage diode while maintaining high voltage capability where needed, thus reducing overall cost while preserving high efficiency and high voltage operation.
Solution Approach 2:
The invention introduces a low voltage diode as an intermediary component between the normally-on high voltage transistor and the high voltage diode. This intermediary low voltage diode handles the forward conduction with ultralow voltage drop, while the high voltage diode provides the necessary voltage blocking capability. This mediation allows the system to achieve both low forward voltage drop and high voltage blocking without requiring an expensive high voltage transistor for the forward conduction path.
2Reliability
If high voltage SiC transistors are used to achieve required I-V behavior, then high voltage operation is achieved, but device complexity and cost increase
Solution Approach 1:
The circuit is segmented into functionally distinct blocks: the normally-on high voltage transistor provides voltage blocking and current conduction, the low voltage diode provides ultralow forward voltage drop, and the high voltage diode provides high voltage blocking. This functional segmentation simplifies the design and analysis of each component while achieving the overall high voltage operation capability, making the circuit more manageable despite the multiple components.
3Ease of manufacture
If simple and cost-effective circuit design is used, then cost is reduced, but achieving high voltage operation and ultralow forward voltage drop becomes difficult
Solution Approach 1:
The invention applies local quality by selecting components with specific properties suited to their local function: the low voltage diode is optimized for low forward voltage drop in the conduction path, while the high voltage diode is optimized for high voltage blocking capability. The normally-on high voltage transistor provides the necessary voltage rating and is normally-on to enable the cascode configuration. This local optimization of component properties allows the circuit to achieve both cost-effectiveness and high performance simultaneously.
Solution Approach 2:
The cascode diode circuit employs a composite structure combining three different semiconductor components with complementary characteristics. The low voltage diode contributes low forward voltage drop, the high voltage diode contributes high voltage blocking, and the normally-on high voltage transistor provides voltage rating and enables the cascode configuration. This composite approach allows the system to achieve performance characteristics that would be difficult to obtain with a single component type, while maintaining cost-effectiveness by using appropriate materials for each specific function.
Data Source
AI summary
Embodiments relate to a cascode diode circuit. The cascode diode circuit comprises a normally on transistor, a low voltage diode and a high voltage diode. The normally on transistor has a gate, a drain, and a source. The low voltage diode has a cathode connected to the source of the normally on transistor and an anode connected to the gate of the normally on transistor. The high voltage diode has a cathode connected to a node between the normally on transistor and the low voltage diode, and an anode connected the drain of the normally on transistor.