Cross-Coupled Level Shift Circuit for Common-Mode Noise Suppression
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Solution Overview
Problem
High-voltage half-bridge driver chips in LiDAR systems generate common-mode noise due to large dV/dt, causing signal interference and loss of duty cycle, which is exacerbated by the need for larger resistors and capacitors to filter noise, leading to reduced signal transmission speed and reliability.
Innovation Solution
A level shift circuit with a cross-coupling module and conversion module using current mirrors to filter common-mode noise without requiring large resistors or capacitors, ensuring high common-mode transient noise suppression and rapid signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filtering module with capacitors and resistors is added to filter common-mode noise, then the noise filtering capability is improved, but the signal transmission speed is reduced due to increased delays
Solution Approach 1:
The patent introduces a level shift circuit as an intermediary component between the high-voltage switching node and the control logic. This level shift circuit actively compensates for common-mode noise through voltage level translation and noise suppression, rather than passively filtering it with RC components. The level shift circuit maintains signal integrity while preserving fast edge rates, thus improving noise filtering without sacrificing signal transmission speed.
Solution Approach 2:
The patent changes the operating parameters of the level shift circuit dynamically. When common-mode noise is detected (through the differential signaling mechanism), the circuit adjusts its voltage level translation parameters to suppress the noise. This allows the circuit to maintain high-speed operation under normal conditions while automatically adapting to filter out noise when present, resolving the contradiction between speed and noise filtering.
2Object-affected harmful factors
If larger resistors or capacitors are used to filter out common-mode noise, then the noise filtering capability is improved, but the delays are increased and signal transmission speed is reduced
Solution Approach 1:
The level shift circuit serves as an active intermediary that processes signals in real-time without requiring large passive components. By using voltage level translation and differential signaling, it achieves noise filtering functionality without the time delays associated with large RC time constants, thus resolving the contradiction between noise filtering and signal transmission delay.
Solution Approach 2:
The patent replaces the passive mechanical filtering approach (using large resistors and capacitors) with an active electronic system (level shift circuit with differential signaling). This substitution eliminates the need for large time-constant components, achieving noise filtering without introducing significant signal transmission delays.
3Productivity
If the power switching device operates at higher frequency and higher voltage, then the productivity and power delivery capability are improved, but the common-mode noise generated is greater
Solution Approach 1:
The level shift circuit acts as an intermediary that isolates the control logic from the high-voltage, high-frequency switching node. It translates the high-voltage switching signals to logic-level signals while suppressing the common-mode noise generated by fast switching, allowing the system to operate at high frequencies and voltages without overwhelming noise interference.
Solution Approach 2:
The differential signaling mechanism in the level shift circuit provides implicit feedback by comparing the voltage levels at its inputs. This allows the circuit to detect and compensate for common-mode noise variations that occur during high-frequency switching, maintaining signal integrity even as switching frequency and voltage increase to improve productivity.
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 solution effectively filters common-mode noise, maintaining signal stability and speed while reducing delays and manufacturing costs, enhancing the reliability of LiDAR systems.
Implementation Method 1
the cross-coupling module comprises a first current mirror and a second current mirror, a first end of the first current mirror is configured to obtain a first current when the first high-voltage switch tube is turned on
Data Source
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AI summary
The embodiment of the present application discloses a level shift circuit and a high-voltage half-bridge driver chip. The level shift circuit includes a first and a second high-voltage switch tube, a cross-coupling module and a conversion module; a controlled end of the first high-voltage switch tube; a controlled end of the second high-voltage switch tube; the cross-coupling module includes a first current mirror and a second current mirror; the first and second nodes of the conversion module are respectively connected to the first and second current mirrors through the first and second nodes, to output an output signal. The level shift circuit can filter out common-mode noise to ensure the stability of the output signal, and does not require the setting of large resistors or capacitors, reduces delays, and improves the speed of signal transmission.