Cryo-CMOS Threshold Offset Compensation for Low-Voltage Qubit Interfaces
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Solution Overview
Problem
Cryogenic cooling of CMOS devices leads to increased threshold voltage variance, limiting power savings due to the need for a larger supply voltage and inconsistent transistor switching, which is exacerbated by atomic-scale disorder and offset charges.
Innovation Solution
Implementing threshold voltage offset compensation through mechanisms like Fowler-Nordheim tunneling and Hot Carrier Injection to modify charge on floating gates, narrowing the distribution of threshold voltages by injecting or removing charge, allowing for reduced supply voltage and lower dynamic power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cryogenic cooling is applied to CMOS devices, then power consumption is reduced, but threshold voltage variance increases
Solution Approach 1:
The patent applies parameter changes by adjusting the threshold voltage of transistors through charge injection or removal in response to detected threshold voltage shifts. This dynamic adjustment compensates for the increased variance caused by cryogenic cooling, allowing the system to maintain consistent transistor switching characteristics while operating at reduced temperatures for lower power consumption.
Solution Approach 2:
The patent implements a feedback mechanism where the system detects threshold voltage shifts in transistors and automatically adjusts their threshold voltages in response. This closed-loop control compensates for the increased variance introduced by cryogenic cooling, ensuring stable operation while maintaining the power savings benefits of low-temperature operation.
2Reliability
If supply voltage is increased to compensate for threshold voltage variance, then transistor switching consistency improves, but power consumption increases
Solution Approach 1:
Instead of increasing supply voltage to compensate for threshold voltage variance, the patent changes the threshold voltage parameter of individual transistors through charge injection. This targeted adjustment maintains switching consistency without requiring a higher supply voltage, thereby preserving the low power consumption benefits of cryogenic operation.
Solution Approach 2:
The patent applies local quality by adjusting the threshold voltage of specific transistors individually rather than increasing the global supply voltage. This localized compensation ensures each transistor switches consistently while maintaining the overall low power consumption regime enabled by cryogenic cooling.
3Manufacturing precision
If threshold voltage offset compensation is implemented, then threshold voltage variation is reduced, but device complexity increases
Solution Approach 1:
The patent implements self-service by having the system automatically detect and compensate for its own threshold voltage shifts without requiring complex external calibration equipment. The compensation mechanism uses simple charge injection circuits that are integrated into the device, reducing the need for complex manufacturing processes while achieving low threshold voltage variation.
Solution Approach 2:
The patent applies preliminary action by pre-characterizing transistor threshold voltages and preparing compensation schemes before full operation. This allows the system to quickly implement threshold voltage adjustments without requiring complex real-time analysis, thereby reducing device complexity while maintaining precise threshold voltage control.
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 method reduces threshold voltage variation, enabling lower supply voltage and quadratic reduction in dynamic power consumption, making cryogenic cooling more viable for power savings.
Implementation Method 1
each of the plurality of devices comprises a floating gate
Implementation Method 2
Implementing threshold voltage offset compensation through mechanisms like Fowler-Nordheim tunneling and Hot Carrier Injection to modify charge on floating gates
Implementation Method 3
Implementing threshold voltage offset compensation through mechanisms like Fowler-Nordheim tunneling and Hot Carrier Injection to modify charge on floating gates
Data Source
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AI summary
Systems and methods related to low power cryo-CMOS circuits with non-volatile threshold voltage offset compensation are provided. A system (400) for interfacing with qubit gates comprises a first plurality of devices (420) configured to operate in a cryogenic environment; a second plurality of devices (430), different from the first plurality of devices (420), configured to operate in the cryogenic environment; and control logic (450). The control logic (450) is coupled to each of the first plurality of devices (420) and the second plurality of devices (430), and is configured to modify a threshold voltage associated with each of the first plurality of devices (420) and the second plurality of devices (430) such that a first threshold voltage associated with each of the first plurality of devices (420) is different from a second threshold voltage associated with each of the second plurality of devices (430).