CAN Transceiver Ground Pin Layout for High-Frequency EMI Reduction
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Solution Overview
Problem
Controller Area Network (CAN) transceivers in automotive systems face challenges in reducing electromagnetic interferences (EMI) at high frequencies due to parasitic resonance circuits formed by the VCC, VIO, and GND pins, leading to increased noise levels above 100 MHz, which are not adequately addressed by common-mode chokes.
Innovation Solution
The implementation of a semiconductor device with separate supply pins for different voltages and a virtual ground node, decoupling the VIO and VCC pins by connecting the output buffer to a ground pad separate from the main GND pin, disrupts the parasitic resonance circuit, thereby reducing electromagnetic emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If common-mode chokes are used to reduce electromagnetic emissions, then high frequency EMI is suppressed, but device complexity and cost increase
Solution Approach 1:
The patent extracts the problematic feedback loop from the circuit by separating the VIO and VCC ground connections. By taking out the parasitic resonance path that involves both supply pins and their shared ground connection, the solution eliminates the need for common-mode chokes while still achieving EMI reduction. The ground pin separation removes the resonance circuit formed by the interaction of VCC, VIO, and GND pins.
Solution Approach 2:
The patent segments the ground connection into separate paths for VCC and VIO supply pins. Instead of using a single common ground connection that creates parasitic resonance, the solution divides the ground path so that each supply pin has its own dedicated ground connection, thereby breaking the resonance loop and reducing high-frequency EMI without adding complex filtering components.
2Object-affected harmful factors
If separate ground connections for VCC and VIO are implemented, then parasitic resonance is disrupted and EMI is reduced, but circuit design complexity increases
Solution Approach 1:
The patent applies local quality by providing differentiated ground connections specifically for the VCC and VIO supply pins, while other parts of the circuit can share common ground connections. This localized separation of ground paths targets the specific source of parasitic resonance without requiring complete ground system segregation, thus reducing EMI with minimal impact on overall circuit design complexity.
Data Source
AI summary
A semiconductor device is described herein. In accordance with one exemplary embodiment the semiconductor device includes a chip package, which includes at least one semiconductor chip, a dedicated ground pin, a first supply pin for receiving a first supply voltage, a second supply pin for receiving a second supply voltage, and a first input pin. The semiconductor device further includes a first circuit integrated in the semiconductor chip, wherein the first circuit is coupled to the first supply pin and to the ground pin, and a second circuit integrated in the semiconductor chip, wherein the second circuit is coupled to the first supply pin and to a virtual ground node. An electronic switch is configured to connect the virtual ground node with the first input pin dependent on the level of a first input signal.