Bias-Protected Level Shifter for Safe Voltage Domain Conversion
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Solution Overview
Problem
Level shifters often malfunction and cause damage to devices operating in different voltage domains due to improper voltage conversion, leading to potential device failure.
Innovation Solution
A level shifter design that includes an inverting circuit, level shifting stage circuit, and buffer stage circuit with input and output protection circuits, utilizing bias voltages applied to gate terminals of switching elements to prevent damage, thereby reducing current consumption and unnecessary power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a level shifter converts voltage between different voltage domains, then voltage conversion is achieved, but device damage may occur due to improper voltage conversion
Solution Approach 1:
The patent applies preliminary action by introducing protection circuits that activate before damage can occur. The first protection circuit clamps input voltages to predetermined safe levels before they can damage the level shifter, and the second protection circuit clamps output voltages before they can damage connected devices. This preventive approach ensures voltage conversion functionality while protecting against overvoltage damage.
Solution Approach 2:
The patent uses protection circuits as intermediary elements between the voltage domains. These circuits act as mediators that manage the voltage conversion process safely by clamping voltages to predetermined levels, thus protecting both the level shifter and connected devices while enabling voltage domain conversion.
2Reliability
If protection circuits are added to prevent device damage, then device safety is improved, but current consumption increases
Solution Approach 1:
The protection circuits operate periodically rather than continuously. The clamping action is activated only when voltage levels exceed predetermined safe thresholds, otherwise the circuits remain inactive. This periodic operation provides protection when needed while minimizing current consumption during normal operation.
Solution Approach 2:
The protection circuits change their operational parameters dynamically. They remain in a high-impedance state during normal operation to minimize current consumption, and switch to a low-impedance clamping state when voltage levels exceed safe thresholds. This parameter change allows the system to maintain device safety while reducing overall current consumption.
Data Source
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AI summary
Provided is a level shifter including: an inverting circuit configured to invert an input voltage and to output an inverted input voltage; a level shifting circuit configured to output first and second intermediate voltages, based on the input and inverted input voltages; and a buffer circuit configured to invert the first and second intermediate voltages, and to output an output voltage and an inverted output voltage, wherein the output and inverted output voltages swing between a first bias voltage and a power supply voltage, wherein the level shifting circuit includes an input protection circuit including input protection switching elements each including a gate terminal connected to a first or a second bias voltage line, and wherein the buffer circuit includes an output protection circuit including output protection switching elements each including a gate terminal connected to the first or second bias voltage line.