Double-Gate Single-Transistor Neuron for Adjustable Firing Thresholds
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Solution Overview
Problem
Current neuromorphic systems face challenges in efficiently adjusting the firing threshold voltage of neurons, which affects their stability and energy consumption, particularly due to the instability of synapses like memristors and the complexity of existing circuitry.
Innovation Solution
A single transistor neuron with a double gate structure, featuring independently separate driving and control gates, allows for the adjustment of firing threshold voltage through a voltage applied to the control gate, enabling homeostasis and reducing energy consumption by integrating signals and inhibiting unnecessary spiking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex circuit including capacitor, integrator, comparator, and reset circuit is used to implement a neuron, then the neuron can perform integrate-and-fire operation, but the device complexity increases and degree of integration is limited
Solution Approach 1:
The patent merges the functions of capacitor, integrator, comparator, and reset circuit into a single transistor neuron device. The transistor's inherent capacitance replaces the external capacitor, the transistor itself performs integration, and the floating body structure provides the firing threshold comparison function, eliminating the need for separate comparator and reset circuits.
Solution Approach 2:
The single transistor structure performs multiple functions simultaneously: it acts as an integrator for incoming signals, a comparator for threshold detection, a capacitor for charge storage in the floating body, and a reset mechanism through controlled discharge. This multi-functionality achieves high integration while maintaining reliable neuron operation.
2Stability of the object's composition
If firing threshold voltage is adjusted to maintain homeostasis and compensate for synapse instability, then neuron stability improves, but the control mechanism becomes more complex
Solution Approach 1:
The single transistor neuron structure provides self-regulation of the firing threshold through its inherent physical properties. The floating body capacitance and transistor characteristics automatically adjust the threshold voltage based on the integrated signal history, eliminating the need for external control circuits while maintaining stability and homeostasis.
3Productivity
If degree of integration is increased to achieve 6 F2 in horizontal structure or 4 F2 in vertical structure, then more neurons can be implemented, but the ability to adjust firing threshold voltage is limited
Solution Approach 1:
The patent enables firing threshold voltage adjustment by changing the gate-to-source voltage parameter of the transistor. By varying the gate voltage, the threshold for firing can be dynamically controlled, allowing adaptation to different operating conditions while maintaining the compact single-transistor structure that achieves high integration density.
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 solution enhances the stability and integration of neurons on neuromorphic chips by eliminating the need for external capacitors and comparator circuits, allowing for precise control of firing threshold voltage and reducing energy consumption.
Implementation Method 1
a floating body layer formed on the barrier material layer
Data Source
AI summary
Disclosed is a single transistor with a double gate structure for an adjustable firing threshold voltage and a neuromorphic system using the same. A single transistor neuron with a double gate structure according to an example embodiment includes a barrier material layer formed on a semiconductor substrate and comprising a hole barrier material or an electron barrier material; a floating body layer formed on the barrier material layer; a source and a drain formed at both sides of the floating body layer, respectively; a driving gate formed at a first side of the floating body layer without contacting the source and the drain; a control gate formed at a second side of the floating body layer without contacting the source and the drain; and a gate insulating film formed between the floating body layer and the driving gate and between the floating body layer and the control gate.