Bidirectional Voltage Level Shifter With Feedback Leakage Control
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Solution Overview
Problem
Conventional digital voltage level shifters experience significant leakage current and long transition times due to the large size of switching devices and inefficient control mechanisms, particularly when transitioning between different logic states.
Innovation Solution
A digital voltage level shifter with a control stage that includes a feedback circuit branch with a control stage switch configured to assume a non-conducting state based on the logical state of the output signal, reducing leakage current and improving transition times by using a low-voltage threshold device and a single path for charging or discharging intermediate nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional voltage level shifters use feedback circuits with pull devices to eliminate static current, then leakage current is reduced, but transition times increase and device footprint increases
Solution Approach 1:
The control stage switch is pre-configured based on the logical state of the output signal before the charging/discharging operation begins. This preliminary configuration ensures that the correct switch state is established in advance, eliminating the delay associated with feedback-based control and reducing transition time while maintaining leakage current reduction
Solution Approach 2:
The circuit is divided into distinct functional stages: a control stage that determines switch states based on output logic, and a charging/discharging stage that executes the voltage transition. This segmentation allows independent optimization of each stage, enabling faster transitions without compromising leakage control
2Power
If conventional voltage level shifters use large switching devices to control voltage transitions, then voltage swing control is improved, but device area increases
Solution Approach 1:
The invention changes the control parameter from direct voltage swing control by large devices to controlled charging/discharging through a single path with smaller devices. The voltage swing is achieved through the controlled accumulation or discharge of charge on intermediate nodes, allowing smaller device dimensions while maintaining effective voltage control
Solution Approach 2:
Intermediate nodes are introduced as mediators between the input and output voltage domains. These nodes store charge temporarily and enable voltage level conversion through controlled charging and discharging cycles, allowing the use of smaller switching devices compared to direct voltage swing control methods
3Power
If conventional voltage level shifters use multiple P-channel FETs in series to control voltage levels, then voltage level shifting is achieved, but current capability is reduced
Solution Approach 1:
The invention extracts the current-limiting P-channel FETs from the main current path and replaces them with a control mechanism that uses smaller switching devices. The current capability is restored by using a single charging/discharging path controlled by the control stage switch, eliminating the series connection of multiple P-channel FETs that degraded current capability
Data Source
AI summary
A dual supply bidirectional level shifter performs voltage level shifting in two directions, low to high and high to low. A feedback control branch and a control stage inverter are provided that reduce leakage power and allow for low delay time while also allowing for a small circuit footprint.