Ultra-Thin Dielectric Current Reference for Stable Low-Power CMOS
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Solution Overview
Problem
Current circuit designs face challenges in providing high-performance at ultra-low power consumption, particularly due to gate leakage in ultra-deep submicron CMOS processes, which affects devices powered by scavenged energy sources and limits their functionality and efficiency.
Innovation Solution
The use of ultra-thin dielectric-layer components, such as transistors or capacitors with dielectric layers less than 3nm thick, to generate stable current and voltage references that are insensitive to variations in operating conditions, by applying a voltage to cause a unidirectional current flow through the dielectric layer, and utilizing driving circuitry to source a reference output current or voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional current reference circuits are used in ultra-deep submicron CMOS processes, then circuit functionality is maintained, but gate leakage current increases power consumption
Solution Approach 1:
The patent converts the harmful gate leakage current into a useful reference current source. By designing the current reference circuit to intentionally exploit the tunneling leakage current through the gate oxide, the circuit transforms this previously unwanted effect into the primary mechanism for generating stable reference currents, thereby eliminating the contradiction between low power consumption and current reference stability
Solution Approach 2:
The patent changes the operating parameters of the MOSFETs by biasing them in the subthreshold region and utilizing gate oxide tunneling currents. This parameter change allows the circuit to operate at ultra-low power levels while maintaining stable current references, as the tunneling current exhibits favorable temperature compensation characteristics that improve overall circuit stability
2Length of moving object
If gate oxide thickness is reduced to enable smaller device geometries, then device scaling is achieved, but gate leakage current increases
Solution Approach 1:
The patent applies the blessing in disguise principle by intentionally designing the current reference circuit to exploit the gate leakage current that results from thin gate oxide. Rather than treating the leakage as a harmful side effect to be eliminated, the circuit is designed so that the tunneling current through the thin oxide becomes the useful reference current source, converting the scaling-induced harm into a beneficial feature
3Use of energy by moving object
If ultra-low bias currents are used to reduce power consumption, then energy efficiency is improved, but reference stability deteriorates
Solution Approach 1:
The patent employs feedback mechanisms through carefully designed current mirrors and transistor configurations that actively stabilize the reference currents. The subthreshold operation and tunneling current mechanisms provide inherent negative feedback that compensates for variations, allowing stable references to be maintained even at ultra-low bias currents of 100nA or less
Solution Approach 2:
The patent changes the operating parameters by utilizing subthreshold MOSFET operation and gate oxide tunneling, which exhibit favorable characteristics at low currents. The tunneling current's exponential relationship with voltage and its temperature dependence provide natural stabilization mechanisms that maintain reference precision even when bias currents are reduced to ultra-low levels
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 stable current and voltage references with low amplitude variations over temperature and power supply changes, enabling efficient operation of low-power circuits with reduced current consumption, suitable for energy-harvesting devices.
Implementation Method 1
the first and second terminals contact the dielectric layer and are physically separated from each other... apply a voltage to the first terminal with respect to the second terminal, in order to cause a unidirectional current to flow through the dielectric layer
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 2A~2B
AI summary
Low-power circuits for providing stable voltage and current references rely on currents flowing through ultra-thin dielectric layer components for operation. A current reference circuit includes driving circuitry operative to apply a voltage to the first terminal of the component with respect to the second terminal of the component in order to cause a current to flow through the dielectric layer, and sources a reference output current that is based on the current flow through the dielectric layer in response to the applied voltage. A voltage reference circuit includes a current source which applies a current to the ultra-thin dielectric layer component, and maintains an output node at a stable reference output voltage level based on the voltage across the ultra-thin dielectric layer component in response to the current flow through the dielectric layer.