HEMT Protection Circuit Diverts Charge to Mitigate Voltage Surges
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Solution Overview
Problem
High electron mobility transistors (HEMTs) are vulnerable to permanent damage from over-voltage or over-current conditions due to the absence of an avalanche effect, which is not present in these devices, unlike silicon-based or GaN transistors, necessitating additional protection mechanisms.
Innovation Solution
Incorporating a protection HEMT in parallel with a power HEMT, where the protection HEMT is initially in an off-state and turns on during triggering events to divert charge and reduce voltage and current surges, with optional resistive coupling or floating gate configurations, to mitigate peak voltage and current spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection mechanism is added to HEMT, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the protection function with an existing HEMT device by connecting a second HEMT in parallel with the first HEMT. This merging approach integrates the protection mechanism into the existing device structure rather than adding completely separate protection components, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The second HEMT serves multiple functions: it acts as a protection device during over-voltage events and can also function as part of the normal circuit operation. This multi-functionality allows the protection mechanism to be achieved without requiring entirely dedicated protection components, thus improving reliability while controlling complexity.
2Device complexity
If HEMT operates without protection, then device complexity is reduced, but reliability deteriorates due to vulnerability to over-voltage
Solution Approach 1:
The second HEMT is pre-configured in parallel with the first HEMT and remains in standby mode during normal operation. When an over-voltage event occurs, the second HEMT quickly activates to provide protection. This preliminary configuration ensures that protection is immediately available when needed without requiring complex real-time detection and activation circuits.
Solution Approach 2:
The second HEMT acts as an intermediary protection element between the voltage source and the first HEMT. During over-voltage events, it diverts excess current and limits voltage spikes, thereby protecting the first HEMT without requiring additional complex protection circuitry.
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
The solution effectively reduces the rate of change of drain-to-source voltage and peak voltage during transient events, minimizing damage to the power HEMT, and can be tailored to achieve desired performance characteristics by adjusting the area and resistance configurations.
Implementation Method 1
turns on during triggering events to divert charge and reduce voltage and current surges
Implementation Method 2
a resistor can be coupled between a source and gate of the protection HEMT, and in another embodiment, the gate can electrically float
Data Source
AI summary
An electronic device can include a drain terminal, a control terminal, and a source terminal, a first HEMT, and a second HEMT. The first HEMT can include a drain electrode coupled to the drain terminal, a gate electrode coupled to the first control terminal, and a source electrode coupled to the source terminal. The second HEMT can include a drain electrode, a gate electrode, and a source electrode. The drain electrode can be coupled to the drain terminal, and the source electrode can be coupled to the source terminal. In an embodiment, a resistor can be coupled between the gate and source electrodes of the second HEMT, and in another embodiment, the gate electrode of the second HEMT can electrically float. During or after a triggering event, the second HEMT can turn on temporarily to divert some of the charging from the triggering event into the second HEMT.