TVS Diode Bridge Circuit for Linear RF Antenna Capacitance
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Solution Overview
Problem
Existing TVS diodes in automotive RF antennas face challenges in providing high energy dissipation with low capacitance, leading to undesirable harmonics in RF signals due to non-linearity, and existing solutions either lack sufficient clamping voltage or capacitance.
Innovation Solution
A TVS diode circuit with asymmetrical or symmetrical configurations, incorporating high-voltage and low-voltage TVS diodes with a diode bridge, providing high energy dissipation and linear capacitance to protect RF antennas from electrostatic overstress and discharge events while minimizing signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a high-voltage TVS diode is used to dissipate transient conditions, then energy dissipation capability is improved, but capacitance non-linearity increases causing undesirable harmonics in the RF signal
Solution Approach 1:
The patent divides the single TVS diode into multiple series-connected TVS diodes (e.g., two diodes D1 and D2 in series). Each diode operates at a lower reverse voltage (e.g., 6V each instead of 12V total), which reduces the capacitance non-linearity effect. The segmentation allows the system to maintain high energy dissipation capability while operating each individual diode in a more linear capacitance region, thereby reducing harmonics in the RF signal.
Solution Approach 2:
The patent changes the operating parameters of the TVS diodes by operating them at lower reverse voltages than their maximum rating. By using series-connected diodes rated for lower voltages (e.g., 6V diodes in series for a 12V system), the capacitance non-linearity is reduced because the diodes operate in a more linear region of their I-V characteristics, while still providing the required energy dissipation capability.
2Device complexity
If a low capacitance TVS diode is used, then capacitance is reduced, but clamping voltage and energy dissipation capabilities are insufficient
Solution Approach 1:
The patent combines multiple TVS diodes in series to achieve the desired performance. The series combination merges the capacitance characteristics to provide lower total capacitance while merging the voltage handling capabilities to provide sufficient clamping voltage and energy dissipation. For example, two 6V-rated diodes in series provide 12V clamping capability and adequate energy dissipation while maintaining low total capacitance.
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 proposed TVS diode circuit effectively dissipates energy and suppresses electrostatic events, maintaining signal integrity by reducing harmonics and ensuring low clamping voltage, suitable for 12V and 24V automotive systems.
Implementation Method 1
TVS diodes are designed to dissipate energy from electrostatic overstress (EOS) and electrostatic discharge (ESD) transient events through breakdown conduction
Implementation Method 2
The TVS diode circuit includes asymmetrical or symmetrical configurations incorporating high-voltage and low-voltage TVS diodes with a diode bridge
Data Source
Figure 1
Figure 2~3
Figure 4~5b
AI summary
A TVS circuit having a first diode with a cathode coupled to a first terminal and an anode coupled to a first node. A second diode has an anode coupled to a second node and a cathode coupled to a third node. A third diode is coupled between the first node and second node. A fourth diode is coupled between the first node and third node. A fifth diode is coupled between the second node and a second terminal. A sixth diode is coupled between the second terminal and the third node. A seventh diode can be coupled between the second terminal and an intermediate node between the fifth diode and sixth diode. The first diode is disposed on a first semiconductor die, while the second diode is disposed on a second semiconductor die. Alternatively, the first diode and second diode are disposed on a single semiconductor die.