Low-Voltage Level Shift Circuit With Balanced Switch Currents
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional level shift circuits are unable to operate effectively at low input voltage levels due to unbalanced current flow through switch elements, resulting in no transitions in output voltages.
Innovation Solution
The proposed level shift circuit incorporates a first and second switch element, a third and fourth switch element, along with a first and second current source module, where the current source modules regulate the current flow to ensure that transitions in output voltages occur by controlling the current through the switch elements, even at low input voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional level shift circuit is used with low input voltage level, then the circuit structure is simple, but the current through P-type FETs is far greater than current through N-type FETs resulting in no voltage transitions
Solution Approach 1:
The current source module is segmented into multiple sub-modules: a first current sub-module connected to the N-type FETs and a second current sub-module connected to the P-type FETs. This segmentation allows independent current control for each FET type, enabling balanced current flow and proper voltage transitions while maintaining circuit functionality.
Solution Approach 2:
The invention changes the current parameter by introducing different current magnitudes for N-type and P-type FETs through the segmented current source module. By adjusting current parameters independently for each FET type, the circuit achieves proper operation at low input voltage levels where conventional circuits fail.
2Reliability
If current source module is added to balance current flow, then voltage transitions are achieved, but device complexity increases
Solution Approach 1:
The current source module serves multiple functions: it provides bias currents to both N-type and P-type FETs, enables voltage transitions, and maintains proper current balancing. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving reliable operation.
Data Source
AI summary
The present invention provides a level shift circuit capable of operating at low input voltage. The level shift circuit comprises: a first switch element coupled to a first output terminal, a second switch element coupled to a second output terminal, a third switch element coupled to the second output terminal and the first output terminal, a fourth switch element coupled to the first output terminal and the second output terminal, a first current source module for letting a current passing through the third switch element smaller than a current passing through the first switch element when the first switch element and the third switch element are conducted, and a second current source module for let a current passing through the fourth switch element smaller than a current passing through the second switch element when the second switch element and the fourth switch element are conducted.