Pulse Transmission Circuit for Higher CMTI in Capacitive Isolation
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Solution Overview
Problem
Existing signal transmission devices employing capacitive insulation methods face challenges in enhancing common mode transient immunity (CMTI) due to signal amplitude attenuation and potential changes in substrate nodes, which can lead to erroneous trigger detection and interference from common mode noise.
Innovation Solution
The implementation of a pulse transmission circuit that causes the transmission pulse signal to make a gradual logic-level transition, and by triggering the transmission pulse signal multiple times during this transition, effectively enhances common mode transient immunity by reducing the impact of common mode noise on trigger detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive insulation method is used to transmit pulse signals between primary and secondary circuit systems, then electrical insulation between the systems is achieved, but common mode noise can cause erroneous trigger detection and reduce common mode transient immunity
Solution Approach 1:
The pulse transmission circuit performs preliminary actions by triggering the transmission pulse signal multiple times before the actual edge detection. This preliminary triggering activates the reception circuit in advance, ensuring that when the actual pulse edge arrives, the reception circuit is already in a ready state and can accurately detect the edge without being affected by common mode noise. The preliminary action prepares the system to withstand the harmful common mode transient interference.
Solution Approach 2:
The invention employs periodic triggering of the transmission pulse signal at regular intervals. This periodic action creates a sequence of trigger pulses that allow the reception circuit to synchronize and stabilize its operation. By using periodic triggering rather than a single isolated pulse, the system can distinguish between regular trigger patterns and abnormal common mode noise events, thereby improving edge detection reliability under capacitive insulation conditions.
2Reliability
If the transmission pulse signal makes a gradual logic-level transition, then common mode transient immunity is enhanced, but the transition time increases
Solution Approach 1:
The gradual logic-level transition is achieved by segmenting the transition process into multiple discrete steps. Instead of a continuous slow transition, the pulse signal progresses through several intermediate logic levels in discrete stages. This segmentation allows the transition to be sufficiently slow to reject common mode noise while maintaining a defined and controlled transition time. Each segment of the transition can be optimized independently to balance immunity and speed requirements.
Solution Approach 2:
The invention introduces dynamic control over the logic-level transition characteristics. The transmission pulse signal's transition rate is made adjustable and adaptable rather than fixed. By dynamically controlling the transition parameters, the system can optimize the balance between transition speed and common mode transient immunity based on operational conditions. This dynamic approach allows the circuit to maintain high reliability while minimizing unnecessary transition time penalties.
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
This approach significantly improves the detection of pulse edges in the reception pulse signal, reducing the likelihood of erroneous operations due to common mode noise, thereby enhancing the overall common mode transient immunity of the signal transmission device.
Implementation Method 1
a capacitor configured to receive the transmission pulse signal output from the pulse transmission circuit and output a reception pulse signal corresponding to the transmission pulse signal
Data Source
AI summary
A pulse transmission circuit is incorporated in a signal transmission device employing a capacitive insulation method, and configured to cause a transmission pulse signal, which is transmitted to a capacitor of a subsequent stage, to make a gradual logic-level transition when a logic level of an input pulse signal switches. For example, the pulse transmission circuit may be configured to trigger the transmission pulse signal a plurality of times, while causing the transmission pulse signal to make a gradual logic-level transition, so as to repeat raising and lowering of the transmission pulse signal.