GaN HEMT Rectifier Circuit With Schottky Diode for Fast Low-Heat Switching
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Solution Overview
Problem
Existing rectifier circuits face limitations in switching speed and heat generation due to threshold forward voltage, particularly in high-current applications, where diodes result in inefficient energy conversion and excessive heat.
Innovation Solution
A rectifier circuit incorporating a depletion mode semiconductor and a hot carrier semiconductor diode, specifically a silicon Schottky diode, configured to operate with a GaN high electron mobility transistor (HEMT), allowing for a high-voltage, low-capacitance design with reduced forward voltage drop and enhanced switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a diode circuit is used for rectification, then the circuit can convert AC to DC, but the threshold forward voltage causes heat generation and reduces efficiency in high current applications
Solution Approach 1:
The patent changes the electrical parameters of the rectifier by using a depletion mode semiconductor device operated in its linear region instead of a diode. This operation mode change reduces the forward voltage drop from typical diode levels (0.7V) to much lower levels, thereby reducing power loss (P=VI) and heat generation in high current applications
Solution Approach 2:
The patent substitutes the traditional diode rectifying mechanism with a depletion mode semiconductor device (such as a JFET or MOSFET) operated in its linear region. This substitution replaces the diode's p-n junction rectification with a field-effect transistor's channel conduction mechanism, which has lower on-resistance and lower voltage drop, improving efficiency and reducing heat
2Speed
If a diode circuit is used for rectification, then the circuit can function as a rectifying element, but the total capacitance limits the switching speed
Solution Approach 1:
The patent changes the electrical parameters by operating the depletion mode device in its linear region rather than using it as a switching device. This operational mode change results in lower effective capacitance values compared to saturated switching operation, thereby improving switching speed while maintaining rectification function
Solution Approach 2:
The patent employs depletion mode semiconductor devices (JFETs or MOSFETs) which have inherently lower capacitance compared to diodes used in high-speed switching applications. These devices provide a favorable capacitance-to-performance ratio that enables faster switching speeds in rectifier circuits
3Ease of operation
If the forward voltage threshold is increased to improve rectification, then the rectifier becomes more conductive, but heat generation becomes unacceptable in high current applications
Solution Approach 1:
The patent optimizes the operating parameters of the depletion mode device by biasing it in its linear region with appropriate gate-source voltage. This parameter optimization achieves low on-resistance for high conductivity while maintaining low voltage drop, thereby reducing power dissipation (P=I²R) and heat generation in high current applications
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 enables efficient energy conversion with reduced heat generation and increased switching speed, suitable for high-voltage applications by leveraging the low forward voltage drop and high-speed characteristics of the GaN HEMT and silicon Schottky diode combination.
Implementation Method 1
the hot carrier semiconductor diode is forward biased to cause an applied voltage at the source node of the depletion mode semiconductor and an applied voltage at the gate node of the depletion mode semiconductor to be slightly different
Implementation Method 2
a depletion mode semiconductor having an output connected to a rectified signal output node of the rectifier circuit
Implementation Method 3
the depletion mode semiconductor includes a GaN high electron mobility transistor (HEMT) circuit
Implementation Method 4
Rectifier circuits convert alternating-current (AC) into direct-current (DC)
Data Source
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AI summary
Provided is a rectifier circuit that includes a depletion mode semiconductor having an output connected to a rectified signal output node of the rectifier circuit and a hot carrier semiconductor diode having a cathode connected to a source node of the depletion mode semiconductor and an anode connected to a gate node of the depletion mode semiconductor. The rectifier may include an alternating current (AC) input node that is connected to the anode of the hot carrier semiconductor diode and the gate node of the depletion mode semiconductor and that is configured to receive an AC input signal.