Level Shift Circuit With Voltage Clamping for Medium-Voltage Nodes
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Solution Overview
Problem
The challenge is to design a level shift circuit using medium-voltage breakdown elements, which is necessary due to the limitations of some process platforms that cannot produce high-breakdown voltage devices, especially in system environments where the maximum voltage difference exceeds 12V.
Innovation Solution
The proposed solution involves a level shift circuit comprising a first voltage clamping module, a second voltage clamping module, and a shift module. These modules adjust input signals and power supply voltages to ensure that the operating and output voltages remain within a controlled range, thereby avoiding device breakdown even when using medium-voltage breakdown elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-voltage breakdown elements (15V) are used to design level shift circuits for system environments with voltage differences exceeding 12V, then the circuit design has high degree of freedom and no reliability problems, but process platforms may only produce medium-voltage breakdown elements (8V)
Solution Approach 1:
The level shift circuit is divided into multiple voltage clamping modules (first voltage clamping module, second voltage clamping module) and a shift module. Each module handles a portion of the voltage range, with the first clamping module adjusting voltage to a first range and the second clamping module adjusting to a second range. This segmentation allows medium-voltage breakdown elements to be used effectively by distributing the voltage handling across multiple stages rather than requiring a single high-voltage element.
Solution Approach 2:
The patent employs bias voltage adjustment to dynamically change the operating parameters of the voltage clamping modules. The first bias voltage and second bias voltage are adjusted to control the clamping levels, allowing the circuit to adapt its voltage ranges according to the specific power supply voltages (first power supply voltage and second power supply voltage) and input signal characteristics. This parameter adjustment enables the circuit to operate reliably with medium-voltage elements across different voltage conditions.
2Ease of manufacture
If medium-voltage breakdown elements (8V) are used in system environments where maximum voltage difference exceeds 12V, then manufacturability is improved, but reliability problems occur
Solution Approach 1:
The circuit is segmented into multiple stages where each voltage clamping module handles a limited voltage range. The first voltage clamping module clamps the input signal to a first range with voltage difference ΔU1, and the second voltage clamping module clamps to a second range with voltage difference ΔU2, where both ΔU1 and ΔU2 are controlled to be within the capabilities of medium-voltage breakdown elements. This multi-stage segmentation allows the overall circuit to handle large voltage differences (>12V) while each individual stage operates within safe voltage limits for medium-voltage elements.
Solution Approach 2:
The voltage clamping modules act as intermediary stages between the input signal and the final output. These intermediate clamping stages progressively reduce the voltage swing at each stage, transforming a large voltage difference input into a controlled output that remains within the breakdown voltage limits of medium-voltage elements throughout the signal path.
3Reliability
If voltage clamping modules are used to control voltage ranges, then device breakdown is avoided, but circuit complexity increases
Solution Approach 1:
The voltage clamping modules serve multiple functions: they clamp the input signal to appropriate voltage levels, adjust the voltage ranges according to bias voltages, and protect subsequent stages from excessive voltage. The same structural blocks (voltage clamping modules with MOS transistors and bias circuits) are reused twice in the circuit (first and second voltage clamping modules), providing a universal solution that handles both signal conditioning and voltage protection in a single integrated approach.
Solution Approach 2:
Rather than using different circuit topologies for different voltage ranges, the patent uses parameter adjustment (bias voltages) to configure the same voltage clamping module structure for different operating conditions. The first bias voltage and second bias voltage can be adjusted to adapt the clamping levels, allowing a single module design to handle multiple voltage scenarios without increasing structural complexity.
Data Source
AI summary
Embodiments of the disclosure provide a level shift circuit, a chip and a display device. By setting first and second voltage clamping modules, and by adjusting first clamping voltage by controlling bias voltage input to the first voltage clamping module and adjusting second clamping voltage by controlling bias voltage and second bias voltage input to the second voltage clamping module, respective operating and output voltages of the first and the second voltage clamping modules and the shift module are within small range. Therefore, even the level shift circuit is designed by using devices with breakdown voltage lower than the difference between the first and second power supply voltages, the devices in the level shift circuit may be avoid being breakdown. Accordingly, some process platforms that cannot produce high-breakdown voltage devices may produce chips including the level shift circuit in the embodiment, and the restrictions on the process platform are reduced.