GaN Reference Voltage Generation Circuit Using Subthreshold Slope Extraction
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Solution Overview
Problem
Existing reference voltage generation circuits using gallium nitride (GaN) devices face significant variations due to process manufacturing and temperature fluctuations, leading to inconsistent reference voltages, especially when based on absolute parameters like threshold voltage, and often require external components like Zener diodes that consume space and increase power consumption.
Innovation Solution
The implementation of a reference voltage generation circuit using enhancement mode (E-mode) GaN high-electron-mobility transistors (HEMTs) that generates a reference voltage by extracting the subthreshold slope of a gate-to-source voltage at different drain current densities through a switching capacitor circuit, eliminating the need for depletion mode GaN devices and external components, thereby reducing variations and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If reference voltage is generated based on absolute parameters of GaN transistors, then the circuit can be simplified, but the reference voltage exhibits large variations due to process manufacturing and temperature fluctuations
Solution Approach 1:
The patent changes the parameter basis from absolute parameters (threshold voltage, conductance) to relative parameters (subthreshold slope). The subthreshold slope is extracted by measuring the change in gate-to-source voltage with respect to drain current at two different current densities, which is inherently less sensitive to process variations and temperature fluctuations than absolute parameters.
Solution Approach 2:
The patent replaces the need for depletion mode GaN devices and external Zener diodes with an enhancement mode GaN HEMT-based circuit that uses electrical field effects and capacitive storage to generate the reference voltage, eliminating mechanical or external component dependencies.
2Reliability
If depletion mode GaN devices and external components like Zener diodes are used, then reference voltage generation is enabled, but the device area and power consumption increase
Solution Approach 1:
The patent merges the reference voltage generation function entirely within the enhancement mode GaN HEMT device itself, using its subthreshold characteristics. The switching capacitor circuit is integrated on-chip, eliminating the need for external Zener diodes and depletion mode devices, thus reducing overall device area while maintaining reference voltage generation capability.
Solution Approach 2:
The patent extracts the reference voltage generation capability from external components and depletion mode devices, concentrating it within the enhancement mode GaN HEMT device using its intrinsic subthreshold slope characteristic, thereby eliminating unnecessary external components and reducing device area.
3Reliability
If depletion mode GaN devices and external components are used, then reference voltage generation is enabled, but power consumption increases
Solution Approach 1:
The enhancement mode GaN HEMT device serves itself to generate the reference voltage by utilizing its own subthreshold slope characteristic. The device measures its own voltage-current relationship and uses integrated capacitors to store and output the reference voltage, eliminating the need for additional power-hungry external components like Zener diodes.
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
This approach provides a stable and reliable reference voltage with reduced variations across different GaN devices and temperatures, improving the performance and efficiency of power conversion systems by eliminating the need for external components and minimizing power consumption.
Implementation Method 1
generates a reference voltage by extracting the subthreshold slope of a gate-to-source voltage at different drain current densities
Implementation Method 2
switching capacitor circuit to generate a reference voltage based on a difference between the first voltage and the second voltage
Data Source
AI summary
Reference voltage generation circuits and related methods are disclosed. An example reference voltage generation circuit includes a voltage generating circuit including an enhancement mode (E-mode) gallium nitride (GaN) transistor, the voltage generating circuit to, in response to a first clock signal having a first phase, generate a first voltage associated with the E-mode GaN transistor, and, in response to a second clock signal having a second phase different from the first phase, generate a second voltage associated with the E-mode GaN transistor, and a switching capacitor circuit coupled to the voltage generating circuit, the switching capacitor circuit to generate a reference voltage based on a difference between the first voltage and the second voltage.