Cross-Coupled NOR Level Shifter for Low-Power High-Speed Translation
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Solution Overview
Problem
Existing voltage level shifters face challenges in efficiently facilitating communication between circuits in different power domains, particularly in shifting signals from a lower power domain to a higher power domain while minimizing power consumption and ensuring reliable performance across varying conditions.
Innovation Solution
The proposed solution involves a voltage level shifter design utilizing cross-coupled NOR gates powered by the higher power domain supply voltage, which enables signal translation by using enable signals to control the level shifting process, thereby reducing leakage current and conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a voltage level shifter is used to facilitate communication between circuits in different power domains, then signal translation capability is improved, but power consumption increases
Solution Approach 1:
The level shifter circuit is designed to be dynamically controllable through an enable signal. The circuit can be switched between active and inactive states, allowing it to operate only when signal translation is required. This dynamic control reduces overall power consumption while maintaining the capability to translate signals between different voltage domains when needed.
Solution Approach 2:
The circuit utilizes different voltage levels (VDD1 and VDD2) to represent logical states, enabling translation between different power domains. By changing the voltage parameter based on the operating domain, the circuit achieves adaptability across different power conditions while managing power consumption through selective activation.
2Adaptability or versatility
If a voltage level shifter operates across varying power conditions, then adaptability is improved, but reliability deteriorates
Solution Approach 1:
The circuit employs different transistor configurations and sizing for different operating domains. Specific transistors are optimized for specific voltage domains, with their characteristics (such as width-to-length ratios) adjusted to ensure reliable operation in each domain. This localized optimization maintains reliability across varying power conditions.
Solution Approach 2:
The circuit design anticipates varying power conditions and incorporates design margins and protective configurations beforehand. The transistor sizing and circuit topology are chosen to ensure stable operation even at the boundaries of different voltage domains, preventing performance degradation before it occurs.
3Adaptability or versatility
If conventional level shifters are used, then basic voltage translation is achieved, but duty cycle distortion increases
Solution Approach 1:
The circuit incorporates feedback mechanisms through cross-coupled transistor configurations that monitor and adjust the output signal characteristics. This feedback ensures that the duty cycle of the translated signal remains accurate and undistorted, maintaining signal integrity across voltage domain transitions.
Solution Approach 2:
The circuit uses asymmetric transistor sizing and configuration to compensate for inherent imbalances in the voltage translation process. By deliberately introducing asymmetric elements, the design counteracts distortion effects and maintains accurate duty cycle representation in the translated signal.
Data Source
Figure 1
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Figure 3A~3B
AI summary
A voltage level shifter includes a first NOR gate (250) having a first input (252) configured to receive a first input signal (D_N) in a first power domain, a second input (255) configured to receive an enable signal (ENB) in a second power domain, a third input (257), and an output (Z). The voltage level shifter also includes a second NOR gate (220) having a first input (222) configured to receive a second input signal (D) in the first power domain, a second input (225) configured to receive the enable signal in the second power domain, a third input (227) coupled to the output of the first NOR gate, and an output (Z_N) coupled to the third input of the first NOR gate. The first and second NOR gates are powered by a supply voltage of the second power domain.