Embedded-Logic Level Shifter for Powered-Down Voltage Domains
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Solution Overview
Problem
Integrated circuits face challenges in managing power consumption, particularly as the number of transistors increases and operating frequency rises, leading to thermal management issues and reduced battery life in battery-powered devices. The introduction of voltage domains to adjust supply voltages independently can result in inaccurate signal transmission when one domain is powered down, causing operational inaccuracies.
Innovation Solution
A level shifter circuit with a shift stage that embeds transistors for logic operations and includes dummy transistors to improve symmetry, ensuring accurate signal transmission between voltage domains by maintaining a predetermined output voltage level when the supply voltage is powered down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the supply voltage is reduced to lower power consumption, then power consumption decreases, but circuit performance deteriorates
Solution Approach 1:
The integrated circuit is divided into multiple voltage domains, each with independently adjustable supply voltages. This allows different regions to operate at optimal voltage levels - some domains can run at higher voltages for peak performance while others operate at lower voltages for reduced power consumption, resolving the contradiction between power efficiency and circuit performance.
2Use of energy by moving object
If voltage domains with independent supply voltages are introduced to manage power, then power consumption management improves, but signal transmission accuracy deteriorates when domains are powered down
Solution Approach 1:
A level shifter circuit is introduced as an intermediary between voltage domains with different supply voltages. The level shifter includes a shift stage with transistors that perform logic operations and dummy transistors that match the logic operation transistors to improve symmetry. This intermediary ensures accurate signal transmission even when source voltage domains are powered down, preventing inaccurate signals from reaching receiving voltage domains while maintaining independent power management.
3Use of energy by moving object
If the supply voltage of a source voltage domain is powered down, then power consumption decreases, but signal accuracy deteriorates causing inaccurate operation
Solution Approach 1:
The level shifter circuit is designed with dummy transistors that match the logic operation transistors in size and configuration. This preliminary design ensures that even when the source voltage domain is powered down, the level shifter maintains proper signal levels and symmetry, preventing inaccurate signals from being transmitted to receiving domains. The dummy transistors are configured to compensate for the powered-down state, ensuring signal integrity is maintained in advance before any potential accuracy issues arise.
Data Source
AI summary
In one embodiment, a level shifter circuit may include a shift stage that also embeds transistors that implement a logic operation on two or more inputs to the level shifter. At least one of the inputs may be sourced from circuitry that is powered by a different power supply than the level shifter and circuitry that receives the level shifter output. Additionally, the level shifter includes one or more dummy transistors that match transistors the perform the logic operation, to improve symmetry of the level shifter circuit. In some embodiments, certain design and layout rules may be applied to the level shifter circuit to limit variation in the symmetry over various manufacturing variations.