Adaptive Power Rails for Integrating Low-Voltage Digital and High-Voltage Analog Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In integrated circuit design, there is a trade-off between achieving high signal-to-noise ratio (SNR) with high supply voltage for analog circuits and using low-voltage, fast CMOS switching devices, as high-voltage-tolerance CMOS devices have slow switching characteristics.
Innovation Solution
The implementation of adaptive power rails that integrate low-voltage thin-gate-oxide devices with high-voltage analog circuits using a common-mode voltage as a reference point, allowing for the generation of adaptive rail voltages that keep the low-voltage devices within their tolerance range while enabling high-voltage supplies for analog circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high supply voltage is used for analog circuits to maximize signal-to-noise ratio, then SNR is improved, but CMOS logic must operate at high supply voltage which increases power consumption and reduces device speed
Solution Approach 1:
The system segments the power supply into multiple independent voltage domains: a high voltage domain (e.g., 2.5V) for analog circuits and a low voltage domain (e.g., 1V) for digital CMOS logic. This segmentation allows each domain to operate at its optimal voltage level, enabling high SNR in analog circuits while maintaining fast switching speeds in digital circuits without requiring the entire system to operate at high voltage.
Solution Approach 2:
The patent applies local quality by providing different voltage characteristics to different parts of the system. Analog circuits receive high voltage to maximize signal amplitude and SNR, while digital circuits receive low voltage to enable fast switching. The adaptive power rail system locally adjusts voltage levels based on the specific requirements of each circuit block, allowing simultaneous optimization of both SNR and switching speed in different regions of the integrated circuit.
2Reliability
If thick-gate-oxide CMOS devices are used to achieve high voltage tolerance, then voltage tolerance is improved, but switching speed becomes 10 times slower than thin-gate-oxide devices
Solution Approach 1:
The system segments device types by voltage requirement, placing thick-gate-oxide devices only in high-voltage analog domains where their voltage tolerance is needed, and thin-gate-oxide devices in low-voltage digital domains where switching speed is critical. This spatial segmentation of device types eliminates the need to compromise on switching speed while maintaining voltage tolerance where required.
Solution Approach 2:
The patent implements local quality by selecting different CMOS device types based on local circuit requirements. Thick-gate-oxide devices are used locally in high-voltage analog circuits where voltage tolerance is the priority, while thin-gate-oxide devices are used locally in low-voltage digital circuits where switching speed is the priority. The adaptive power rail system ensures each device type operates within its optimal voltage range.
3Measurement precision
If high supply voltage is used throughout the system to accommodate high input signal amplitude, then SNR is improved, but power consumption increases due to high voltage operation of entire system
Solution Approach 1:
The system segments the power distribution into high-voltage and low-voltage rails, allowing only the analog circuits that require high signal amplitude to consume high power, while digital circuits operate on low-voltage rails and consume minimal power. This segmentation dramatically reduces overall system power consumption compared to a unified high-voltage system, while still achieving high SNR in the analog domain.
Solution Approach 2:
The patent applies local quality by providing high voltage locally only to analog circuits that require it for high SNR performance, while digital circuits receive low voltage for efficient operation. The adaptive power rail system locally adjusts power delivery based on circuit type and requirements, minimizing unnecessary power consumption in low-voltage-tolerance circuits while maintaining high signal quality where needed.
Data Source
AI summary
According to one disclosed embodiment, an adaptive voltage rail circuit for integrating low voltage devices with high voltage analog circuits is described. This adaptive voltage rail circuit includes a high voltage analog circuit having a common mode voltage. Further included is a first voltage rail having a first rail voltage which is based on and greater than the common mode voltage of the high voltage analog circuit. A second voltage rail having a second rail voltage which is based on and less than the same common mode voltage is also present. By connecting these first and second voltage rails across at least one low voltage device, an adaptive voltage rail circuit is able to safely integrate low voltage devices with high voltage analog circuits in the same system.