Integrated Level-Shifting Logic for Cross-Domain Signal Switching
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Solution Overview
Problem
Combinatorial circuits in modern data processing systems face performance issues and power consumption challenges due to increasing voltage differences between different voltage domains, particularly in integrated circuits where level shifting is required to maintain stability and reduce power consumption.
Innovation Solution
An integrated level shifting combinatorial circuit is developed, splitting combinatorial circuitry between two voltage domains with feedback and contention mitigation circuitry to apply level shifting functions, reducing voltage drops and power consumption while enabling large range level shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional separate level shifter circuit is used to pass signals between voltage domains, then level shifting function is achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines the level shifting function with the combinatorial circuit by integrating a level shifter within the circuit structure. The level shifter includes a first transistor in the first voltage domain and a second transistor in the second voltage domain, allowing the combinatorial circuit to perform both computation and level shifting operations in a unified structure, thereby reducing overall device complexity while maintaining reliable signal transmission between voltage domains.
2Reliability
If a separate level shifter circuit is used, then level shifting is achieved, but power consumption increases
Solution Approach 1:
By merging the level shifting function into the combinatorial circuit, the patent eliminates the need for a separate dedicated level shifter circuit. The integrated level shifter uses transistors that are already part of the combinatorial logic structure, allowing signal level translation to occur as a byproduct of the logical operations rather than requiring additional active circuitry, thus reducing overall power consumption.
Solution Approach 2:
The combinatorial circuit is designed to serve multiple functions: it performs its primary combinatorial logic operation while simultaneously providing level shifting capability. This multi-functionality means that the same circuit components are utilized for both computation and voltage domain translation, eliminating the need for separate dedicated circuits and thereby reducing total power consumption.
3Use of energy by moving object
If voltage difference between domains increases to reduce power consumption in low voltage domain, then power consumption is reduced, but performance and reliability deteriorate
Solution Approach 1:
The patent segments the circuit into two distinct voltage domain portions: a first portion operating in the first voltage domain and a second portion operating in the second voltage domain. The level shifter is positioned at the boundary between these segments, allowing each segment to be optimized for its respective voltage domain. This segmentation enables the low voltage domain to operate at reduced power while the level shifter reliably bridges the voltage difference, maintaining signal transmission reliability.
Solution Approach 2:
The level shifter acts as an intermediary component between the two voltage domains. It includes a first transistor in the first voltage domain and a second transistor in the second voltage domain, creating a bridging structure that facilitates reliable signal transmission across the voltage boundary. This intermediary structure allows the system to exploit large voltage differences for power savings while maintaining reliable signal integrity through the controlled transition provided by the level shifter.
4Use of energy by moving object
If combinatorial circuit operates entirely in low voltage domain, then power consumption is reduced, but output signal cannot drive high voltage domain components
Solution Approach 1:
The combinatorial circuit is divided into two segments: a first segment that performs the primary combinatorial logic operation in the low voltage domain to minimize power consumption, and a second segment in the high voltage domain that provides output buffering and driving capability. This segmentation allows the circuit to benefit from low voltage operation while still maintaining the ability to drive high voltage domain components through the high voltage output stage.
Solution Approach 2:
The level shifter serves as an intermediary between the low voltage combinatorial logic and the high voltage output stage. It translates the low voltage signal from the combinatorial logic into a high voltage signal that can properly drive components in the high voltage domain, thereby enabling the system to operate primarily in the low voltage domain for power efficiency while maintaining full driving capability in the high voltage domain.
Data Source
AI summary
An integrated level shifting combinatorial circuit receives a plurality of input signals in a first voltage domain and performs a combinatorial operation to generate an output signal in a second voltage domain. The circuit includes combinatorial circuitry includes first and second combinatorial circuit portions operating in respective first and second voltage domains. The second combinatorial circuit portion has an output node whose voltage level identifies a value of the output signal and includes feedback circuitry which applies a level shifting function to an intermediate signal generated by the first combinatorial circuit portion. A contention mitigation circuitry reduces a voltage drop across at least one component within the feedback circuitry in situations when the combinatorial circuitry's performance of the combinatorial operation causes the combinatorial circuitry to switch the voltage on the output node, the contention mitigation circuitry thereby assists the combinatorial circuitry in the output node voltage switching.