Full-Swing Voltage Conversion Circuit for Subthreshold Level Shifting
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Solution Overview
Problem
Traditional level-shifters face challenges in converting signals from a low voltage domain to a high voltage domain, particularly from a subthreshold voltage domain, due to intense competition between pull-up and pull-down networks, resulting in large power leakage, a narrow input voltage range, and long conversion delays.
Innovation Solution
A full swing voltage conversion circuit is introduced, featuring an auxiliary pull-down unit with multiple NMOS transistors connected in series, which improves the conversion unit's ability to recognize differential input signals by forming additional pull-down paths, enabling effective conversion from a low voltage to a high voltage domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional level-shifter uses cross-coupled PMOS transistors and pull-down NMOS transistors for voltage conversion from low voltage domain to high voltage domain, then the circuit structure is simple, but the power leakage is large, input voltage range is narrow, and conversion delay is long
Solution Approach 1:
The level-shifter circuit is divided into multiple independent modules: differential input unit, conversion unit, auxiliary pull-down unit, and output driving unit. Each unit performs a specific function, allowing optimized design of pull-up and pull-down paths separately to reduce power leakage while maintaining simplicity.
Solution Approach 2:
The auxiliary pull-down unit acts as an intermediary between the differential input unit and conversion unit, providing additional pull-down paths that improve signal recognition capability without significantly increasing overall circuit complexity.
2Device complexity
If a traditional level-shifter uses cross-coupled PMOS transistors and pull-down NMOS transistors for voltage conversion, then the circuit structure is simple, but the input voltage range is narrow
Solution Approach 1:
The circuit employs dynamic control of pull-down paths through the auxiliary pull-down unit, which is activated based on differential input signals. This dynamic adjustment allows the circuit to adapt to different input voltage conditions and expand the effective input voltage range.
Solution Approach 2:
The invention changes the electrical parameters of the pull-down network by introducing additional NMOS transistors with different threshold voltages, allowing the circuit to handle a broader range of input voltages while maintaining a relatively simple overall structure.
3Device complexity
If a traditional level-shifter uses cross-coupled PMOS transistors and pull-down NMOS transistors for voltage conversion, then the circuit structure is simple, but the conversion delay is long
Solution Approach 1:
The auxiliary pull-down unit prepares additional pull-down paths in advance, which are quickly activated when differential input signals are detected. This preliminary preparation reduces the time required for voltage conversion by having ready-to-use pathways for signal transition.
Solution Approach 2:
The circuit maintains continuous pull-down capability through the auxiliary unit, ensuring that the conversion process can proceed without interruption or waiting periods, thereby reducing overall conversion delay while keeping the circuit structure relatively simple.
4Adaptability or versatility
If a subthreshold level-shifter uses multiple threshold voltage PMOS transistors and low threshold voltage NMOS transistors, then the input voltage range is expanded, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
Instead of using multiple threshold voltage PMOS transistors throughout the circuit, the invention applies different threshold voltage characteristics locally - using standard PMOS transistors in the cross-coupled pair and auxiliary pull-down unit, while only employing low threshold voltage NMOS transistors where specifically needed for pull-down functionality. This localized approach expands input voltage range while controlling overall complexity.
5Adaptability or versatility
If a subthreshold level-shifter uses multiple threshold voltage PMOS transistors and low threshold voltage NMOS transistors, then the input voltage range is expanded, but the production difficulty increases
Solution Approach 1:
The invention strategically changes threshold voltage parameters only where necessary - using low threshold voltage NMOS transistors specifically in the auxiliary pull-down unit and input stage, while maintaining standard PMOS transistors in the cross-coupled pair. This selective parameter change expands input voltage range while minimizing production complexity compared to using multiple threshold voltage variants throughout the entire circuit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The full swing voltage conversion circuit efficiently converts low voltage signals to high voltage signals, reducing power consumption and improving conversion speed by utilizing the auxiliary pull-down unit to enhance signal recognition and output voltage.
Implementation Method 1
an auxiliary pull-down unit between the input terminal and the conversion unit for receiving a feedback signal from the output driving unit. In the full swing voltage conversion circuit, capability of the conversion unit in recognizing the differential input unit is improved by turning on the auxiliary pull-down unit to form auxiliary pull-down paths of the conversion unit.
Data Source
AI summary
The invention provides a full swing voltage conversion circuit. The full swing voltage conversion circuit comprises: an input terminal for inputting a first level signal; an output terminal for outputting a second level signal; a differential input unit for inverting the first level signal of the input terminal, and outputting a differential input signal; a conversion unit; and an output driving unit; wherein the full swing voltage conversion circuit further comprises an auxiliary pull-down unit between the input terminal and the conversion unit for receiving a feedback to improve capability of the conversion unit in recognizing the differential input signal, such that the full swing voltage conversion circuit of the invention can convert from inputting a low voltage to outputting a high voltage.