Integrated Bias Circuit for Bidirectional Switch Voltage Blocking
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Solution Overview
Problem
Existing bidirectional switches face challenges in achieving low on-state resistance, high switching speed, and efficient voltage blocking, particularly in medium-voltage and low-voltage applications, due to the complexity and size of dual-gate structures and the difficulty in integrating bias circuits for single-gate switches.
Innovation Solution
A simplified bias circuit using small GaN-based HEMTs is integrated with the bidirectional switch to provide a virtual source voltage level, reducing on-state resistance and ensuring proper switching, while a high-pass circuit handles fast voltage changes, without additional control circuits or quiescent current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual-gate structure is used to achieve bidirectional switching, then voltage blocking capability is improved, but device complexity and size increase
Solution Approach 1:
The bidirectional switch is segmented into two unidirectional switches with shared source/drain regions, where each transistor handles one polarity. This segmentation allows independent optimization of each transistor while achieving bidirectional functionality, reducing overall complexity compared to a monolithic dual-gate structure.
Solution Approach 2:
The shared source and drain regions serve multiple functions: they act as source for one transistor and drain for the other, enabling both transistors to operate with common terminals. This multi-functionality reduces the number of required terminals and simplifies the overall device structure while maintaining bidirectional voltage blocking capability.
2Productivity
If a bias circuit is integrated to provide virtual source voltage, then switching performance is improved, but device complexity increases
Solution Approach 1:
The bias circuit is merged with the main switching circuit by using the same transistor structures and shared terminals. The virtual source node is created by combining the source terminals of both transistors, eliminating the need for separate bias generation circuits and reducing overall device complexity while improving switching performance.
Solution Approach 2:
The bias circuit utilizes the transistors' own characteristics and internal voltage distributions to generate the virtual source voltage, rather than requiring external bias circuits. The transistors self-generate the necessary gate-to-source voltage through their operational characteristics, eliminating the need for additional control circuits.
3Loss of energy
If transistor size is reduced to lower on-state resistance, then power loss is reduced, but voltage blocking capability deteriorates
Solution Approach 1:
The device transitions from a planar structure to a three-dimensional stacked configuration where transistors are vertically arranged with shared terminals. This dimensional change allows compact integration while maintaining adequate breakdown voltage through increased channel length in the vertical direction, enabling reduced footprint without sacrificing voltage blocking capability.
Data Source
AI summary
An integrated circuit includes a driver circuit having a driver input, a driver output, a power terminal, and a reference terminal; and a bias circuit having a first terminal, a second terminal, a bias control terminal, and a bias output. The bias output is coupled to the reference terminal. The bias circuit includes a first transistor coupled between the first terminal and the bias output, and a second transistor coupled between the bias output and the second terminal. The first transistor has a first control terminal, the second transistor has a second control terminal, and the first control terminal and the second control terminal are coupled to the bias control terminal to receive a same control signal from the bias control terminal.