Integrated GaN HEMT Capacitor Diode for Single-Supply Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wide gap semiconductor devices, such as AlGaN/GaN HEMTs, require a negative power supply for normally-on operation, leading to increased circuit complexity and component count, along with voltage oscillations due to parasitic inductances in the wiring, which complicates switching operations.
Innovation Solution
A semiconductor device configuration that integrates a normally-on type FET, a capacitor with one electrode connected to the gate, and a diode with the anode connected to the gate and cathode connected to the source, all formed on the same chip, allowing switching operations with a single power supply and reducing wiring length and component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative power supply is used for normally-on HEMT operation, then the HEMT can be turned off by applying negative gate voltage, but the number of circuit components increases and wiring becomes complex
Solution Approach 1:
The patent combines the capacitor and diode that were previously external components into an integrated structure formed on the same chip as the HEMT. The capacitor is formed with first and second electrodes where the first electrode overlaps the gate electrode, and the diode is formed with its anode connected to the gate, creating a compact integrated circuit that eliminates the need for separate negative power supply connections.
Solution Approach 2:
The patent utilizes vertical stacking and overlapping structures in the capacitor formation, where the first electrode overlaps the gate electrode in a planar dimension while being separated by a dielectric layer. This three-dimensional arrangement allows the capacitor to be formed within the chip area without increasing the footprint, effectively integrating multiple functions in a compact space.
2Ease of operation
If external capacitor and diode are provided for normally-on HEMT circuit, then switching operation can be achieved without negative power supply, but the number of external components increases
Solution Approach 1:
The patent merges the capacitor and diode functions into structures that are formed on the same chip as the HEMT device. The capacitor comprises first and second electrodes with the first electrode overlapping the gate electrode, and the diode has its anode connected to the gate, eliminating the need for separate external components and reducing the overall component count while maintaining the switching functionality.
3Ease of manufacture
If wiring length from driving circuit to gate is increased, then circuit layout flexibility improves, but voltage oscillation (ringing) is generated by parasitic inductances
Solution Approach 1:
The patent extracts the capacitor and diode functions from external components and integrates them directly onto the chip with the HEMT gate. This integration dramatically reduces the wiring length between the driving circuit and the gate, minimizing parasitic inductances and suppressing voltage oscillations while maintaining layout flexibility through the integrated structure design.
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
Enables compact circuit design with reduced wiring length and suppressed voltage oscillations, effectively performing switching operations without a negative power supply, thereby simplifying the circuit and minimizing noise.
Implementation Method 1
a capacitor having one electrode electrically connected to a gate of the FET and the other electrode electrically connected to an input terminal
Implementation Method 2
a diode having an anode electrode electrically connected to the gate of the FET and a cathode electrode electrically connected to a source of the FET
Data Source
AI summary
In an embodiment, provided is a semiconductor device in which a normally-on type FET; a capacitor having one electrode electrically connected to a gate of the FET and the other electrode electrically connected to an input terminal; and a diode having an anode electrode electrically connected to the gate of the FET and a cathode electrode electrically connected to a source of the FET are formed on the same chip on which the FET is formed. Also, the capacitor may have a structure in which an insulation film such as a dielectric substance is formed on a gate drawn electrode of the FET, and a metallic layer is formed on the insulation layer.