Positive Feedback Transistor Circuit for Low Power Neuron Emulation
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Solution Overview
Problem
Existing semiconductor circuits for emulating neuron firing processes require high supply voltages and suffer from high power consumption due to continuous current flow even when the neuron is not fired, limiting their integration and energy efficiency.
Innovation Solution
A semiconductor circuit utilizing a positive feedback transistor with two gates in series, connected to a first n-channel MOSFET and a p-channel MOSFET, along with an inverter, to minimize power consumption by allowing current to flow only during neuron firing, using a unique doping structure and gate configuration to manage electron and hole accumulation in the channel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional capacitor is used to store charge in the neuron circuit, then the circuit can emulate neuron firing, but the area of the circuit becomes large and power consumption increases when the neuron is not fired
Solution Approach 1:
The patent changes the fundamental parameter of charge storage from using a capacitor to using a floating body device where holes are stored in the body region. This parameter change eliminates the need for a separate capacitor component, reducing circuit area while also eliminating continuous leakage current, thereby reducing power consumption when the neuron is not fired.
Solution Approach 2:
The patent extracts the charge storage function from a separate capacitor component and integrates it into the floating body device itself. The holes generated by impact ionization are stored directly in the floating body, eliminating the need for an external capacitor and its associated leakage current problems.
2Reliability
If a conventional capacitor-based neuron circuit is used, then neuron firing can be emulated, but current continues to flow even when the neuron is not fired, causing high power consumption
Solution Approach 1:
The patent implements periodic action by ensuring current flows only during the brief moment when the neuron fires (when the threshold is exceeded and impact ionization occurs). When the neuron is not fired, the floating body holds the charge without continuous current flow, creating a periodic rather than continuous power consumption pattern that matches biological neuron behavior.
Solution Approach 2:
The patent converts the typically harmful leakage current of capacitors into a beneficial feature by using the floating body's ability to hold charge without continuous current. The impact ionization process that generates holes is harnessed to create a stable, non-leaking charge storage mechanism that eliminates power wastage.
3Area of stationary object
If holes are stored in the floating body using impact ionization, then the circuit area is reduced, but a relatively high supply voltage is required and device endurance deteriorates
Solution Approach 1:
The patent implements feedback through the positive feedback transistor where the stored holes in the floating body modulate the channel conductivity, which in turn affects the current flow and impact ionization rate. This feedback mechanism allows the system to self-regulate and maintain stable operation with reduced supply voltage while preserving device endurance through controlled charge accumulation and discharge cycles.
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 reduces power wastage significantly by ensuring current is only active during neuron firing, achieving low power operation and comparable endurance to general MOSFETs while maintaining efficient signal transmission.
Implementation Method 1
when holes formed by impact ionization are stored in the floating body
Implementation Method 2
positive feedback field effect transistor (FBFET)
Data Source
AI summary
Semiconductor circuits are provided for emulating neuron firing process using a positive feedback transistor having first and second gate electrodes in the longitudinal direction of a channel region. The first gate electrode is connected to a gate electrode of a first p-channel MOSFET to be an input terminal and the second gate electrode is connected to a drain to be applied with a supply voltage. Thus electrons and holes can accumulate separately in a channel region (i.e., a body) under each of the gate electrodes by applying input signals to the input terminal and drastically reduce the wasted power consumption in the non-fired neurons because the current is turned on and off only at a moment that corresponds to a firing of the neuron. Thus, the semiconductor circuits can be driven by low power and have the same level of endurance as a general MOSFET.