3D Flip-Flop Level Shifting for Cross-Power Domain Data Transfer
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Solution Overview
Problem
Existing integrated circuit designs face inefficiencies in area consumption, power consumption, write time delay, and cross-talk across power domains due to the need for level shifter circuitry in multi-power domain systems, which hinders the adoption of fine-grained multi-power domain designs in high-performance applications.
Innovation Solution
A multi-stage cross power domain interface is implemented using a master-slave flip-flop configuration with a level shifter and isolation circuitry, where the slave flip-flop operates in a different power domain, reducing area and power consumption by integrating level shifting and storage functions within a 3D IC structure, and utilizing monolithic inter-tier vias to separate power rails, thereby minimizing cross-talk and congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If level shifter circuitry is added to transfer data across power domains, then data transfer reliability is improved, but area consumption and power consumption increase
Solution Approach 1:
The patent combines the level shifter circuitry with the flip-flop storage element into a single integrated structure. The level shifter is merged with either the master or slave flip-flop stage, eliminating the need for separate level shifter components and reducing overall area consumption while maintaining data transfer reliability across power domains.
Solution Approach 2:
The flip-flop circuit is designed to perform multiple functions: data storage and level shifting across power domains. By making the flip-flop multi-functional, the patent eliminates the need for dedicated level shifter circuitry, thereby reducing area consumption while maintaining the ability to transfer data reliably between different power domains.
2Reliability
If level shifter circuitry is added to transfer data across power domains, then data transfer reliability is improved, but power consumption increases
Solution Approach 1:
The level shifter functionality is merged into the flip-flop circuit, allowing data transfer across power domains using the existing flip-flop power consumption characteristics rather than adding separate power-hungry level shifter circuitry.
Solution Approach 2:
The flip-flop is designed to perform both storage and level shifting functions, reducing the need for additional power-consuming circuits. The multi-functional design ensures that power consumption is optimized while maintaining reliable data transfer across power domain boundaries.
3Adaptability or versatility
If separate power rails are provided for multiple power domains, then power management flexibility is improved, but power rail physical routing congestion increases
Solution Approach 1:
The patent transitions from a planar 2D layout to a 3D stacked architecture, where master and slave flip-flop stages are placed in different vertical tiers. This dimensional change allows power rails to be routed separately in the vertical dimension, reducing horizontal routing congestion while maintaining multiple power domains for flexible power management.
Solution Approach 2:
The flip-flop circuit is segmented into master and slave stages located in different 3D tiers, with each stage having its own power rail. This segmentation allows independent power rail routing for each power domain, reducing routing congestion while maintaining power management flexibility.
4Use of energy by stationary object
If fine-grained power domains are used to reduce system power, then power consumption is reduced, but area consumption and write time delay increase due to level shifter requirements
Solution Approach 1:
The level shifter is merged with the flip-flop circuit, enabling fine-grained power domain implementation without the area overhead of separate level shifter components. This allows multiple fine-grained power domains to be used for power reduction while avoiding the area consumption penalty.
Solution Approach 2:
The flip-flop is designed as a multi-functional element that handles both data storage and level shifting between fine-grained power domains. This eliminates the need for additional area-consuming level shifter circuitry, enabling fine-grained power domain implementation for system power reduction without area penalties.
5Use of energy by stationary object
If fine-grained power domains are used to reduce system power, then power consumption is reduced, but write time delay increases due to level shifter requirements
Solution Approach 1:
The level shifter is merged with the flip-flop circuit, allowing data transfer between fine-grained power domains to occur within the same write cycle without additional delay from separate level shifter stages. This maintains fast write performance while enabling power consumption reduction through fine-grained power domains.
Solution Approach 2:
The multi-functional flip-flop performs level shifting internally during the write operation, eliminating external level shifter delay. This enables fine-grained power domain implementation for power reduction without the write time delay penalty that would result from separate level shifter circuits.
Data Source
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AI summary
The disclosed embodiments comprise a multi-stage circuit (10) operating across different power domains (A, B). The multi-stage circuit may be implemented as a master-slave flip-flop circuit (10c) integrated with a level shifter (65c) that transfers data across different power domains. The master and slave stages of the flip-flop may be split across two tiers (102, 104) of a 3D IC and may include (i) a level shifter across different power domain integrated within the flip-flop circuit, (ii) reduced one-state writing delays by a self-induced power collapsing technique, (iii) splitting flip-flop power supplies in different tiers using monolithic 3D IC technology, and (iv) cross power domain data transfer between 3D IC tiers.