Programmable Hysteretic Comparator Circuit for GaN Noise Immunity
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Solution Overview
Problem
Existing hysteretic comparators in GaN are process-dependent due to variability in GaN Vth, and they lack effective noise protection and programmability.
Innovation Solution
A circuit comprising a comparator, a transistor, and a depletion mode device with a control gate, where the transistor's output controls the pinch-off voltage of the depletion mode device, providing noise protection and programmability independent of GaN Vt, using a fixed reference voltage and a moving voltage for hysteresis control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multiplier based on GaN HEMT Vth is used for setting hysteresis voltage, then the hysteresis can be controlled, but the hysteresis becomes extremely process dependent due to GaN Vth variability
Solution Approach 1:
The patent changes the controlling parameter from GaN Vth (which varies with process) to a separate reference voltage Vref that can be independently controlled. The hysteresis voltage is now determined by the ratio of resistors and the reference voltage level, not by the transistor threshold voltage, thereby decoupling hysteresis control from process variations.
Solution Approach 2:
The patent introduces an intermediary reference voltage source and resistor divider network between the power supply and the hysteresis control node. This intermediary structure allows precise control of hysteresis voltage through external voltage references rather than relying directly on device parameters that vary with manufacturing processes.
2Reliability
If existing hysteretic comparator circuits are used, then comparison function is provided, but noise protection is insufficient and programmability is limited
Solution Approach 1:
The patent makes the hysteresis voltage dynamic and programmable by allowing the reference voltage Vref to be adjusted externally. The circuit can adapt its hysteresis characteristics based on external control signals, enabling programmability while maintaining noise rejection through the hysteresis mechanism.
Solution Approach 2:
The patent employs positive feedback through the resistor network connected to the output to create hysteresis. This feedback mechanism provides noise protection by creating distinct threshold levels for rising and falling inputs, while the reference voltage allows programmable control of these threshold levels.
Data Source
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AI summary
The present disclosure relates to a circuit and, more particularly, to comparator circuits used with a depletion mode device and methods of operation. The circuit includes: a comparator; a transistor connected to an output of the comparator; and a depletion mode device connected to ground and comprising a control gate connected to the transistor.