Leakage Compensation Circuit for FinFET Gate Current Cancellation
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Solution Overview
Problem
MOS devices, particularly FinFETs, suffer from significant gate leakage currents due to the gate-tunneling effect, which limits circuit performance and is exacerbated by smaller gate thicknesses and high temperatures, and existing leakage-current compensation circuits have performance shortcomings, especially in new technologies with limited voltage headroom.
Innovation Solution
A leakage-current compensation circuit that includes a first node for a leakage current, a second node for a mirrored leakage current, a current mirror to generate a compensation current, and a differential amplifier to control a feedback component, allowing the second potential difference to track the first potential difference, thereby enabling the compensation current to partially cancel out the leakage current with improved accuracy across a broader bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If gate thickness is reduced to scale down device size, then device integration density is improved, but gate leakage current increases due to enhanced gate-tunneling effect
Solution Approach 1:
The patent converts the harmful gate leakage current into a useful compensation signal. By replicating the leakage current through a current mirror and injecting it with opposite polarity, the circuit transforms the harmful tunneling effect into a beneficial compensation mechanism that cancels out the original leakage current, thereby maintaining circuit performance despite reduced gate thickness
Solution Approach 2:
The patent changes the electrical parameters (current magnitude and polarity) to compensate for gate leakage. By adjusting the compensation current to match the leakage current's magnitude while reversing its polarity, the system dynamically adapts to varying leakage conditions caused by reduced gate thickness, temperature changes, and voltage variations
2Productivity
If FinFET technology is used to improve device performance, then transistor efficiency is enhanced, but gate leakage current increases due to three-sided gate surrounding the channel
Solution Approach 1:
The patent applies the same compensation technique to FinFET devices, converting their increased gate leakage (caused by the three-sided gate structure) into a compensatable signal. The current mirror replicates and inverts the leakage current, allowing FinFETs to maintain their high efficiency while suppressing the harmful leakage effect through active compensation
3Object-generated harmful factors
If leakage-current compensation circuits are added to reduce leakage current, then circuit performance is improved, but voltage headroom is reduced due to additional circuit components
Solution Approach 1:
The patent uses a current mirror to create a copy of the leakage current without requiring additional voltage headroom. By replicating the leakage signal through matched transistors and injecting the inverted copy, the system achieves compensation using only current copying mechanisms that operate within the existing voltage constraints, avoiding the need for additional voltage drops
4Object-generated harmful factors
If conventional leakage compensation methods are used, then some leakage current is compensated, but compensation accuracy is insufficient for new technologies with limited voltage headroom
Solution Approach 1:
The patent implements a feedback mechanism where the compensation current is continuously adjusted based on the actual leakage current magnitude. The current mirror configuration provides automatic feedback by replicating the leakage signal and adjusting the compensation injection to maintain accurate cancellation, achieving high compensation accuracy even in technologies with limited voltage headroom
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 effectively reduces the impact of leakage currents on MOS devices, enhancing circuit performance by accurately compensating for leakage currents across both AC and DC components, thus improving the reliability of MOS devices in applications like PLLs and VCOs.
Implementation Method 1
a current mirror connected to the first node and the second node and configured to cause a compensation current to flow through the first node with opposite polarity to the first leakage current with respect to the first node, the magnitude of the compensation current dependent on the magnitude of the second leakage current due to current mirroring
Implementation Method 2
a differential amplifier configured, based on a difference between the first potential difference and the second potential difference, to control a feedback component connected in series with the second component along a current path carrying the second leakage current to cause the second potential difference to track the first potential difference
Implementation Method 3
an AC coupling connected to superimpose an AC-component of the first potential difference on the second potential difference
Implementation Method 4
MOS (metal oxide semiconductor) devices suffer from gate leakage due to a gate-tunneling effect
Data Source
AI summary
A leakage-current compensation circuit including: a first node for connection of a first component, a first leakage current flows through the first component and node with a given polarity, the magnitude of the first leakage current dependent on a first potential difference across the first component; a second component connected to a second node with a second leakage current flowing through the second component and node, the magnitude of the second leakage current dependent on a second potential difference across the second component; a current mirror connected to the first and second nodes to cause a compensation current, the magnitude of the compensation current dependent on the magnitude of the second leakage current; a differential amplifier connected in series with the second component along a current path carrying the second leakage current; and an AC coupling superimposing an AC-component of the first potential difference on the second potential difference.