Reverse Current Suppression Circuit for PMOS Transistors
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Solution Overview
Problem
High-voltage devices with thin gate oxide PMOS transistors face challenges in maintaining voltage control between the gate and substrate, leading to low withstandable voltage and increased manufacturing complexity and cost, necessitating a reverse current suppression circuit to protect these devices.
Innovation Solution
A reverse current suppression circuit is designed for high-voltage-withstanding thin gate oxide PMOS transistors, incorporating a gate drive unit and substrate switching unit that control the transistor's operation to prevent reverse current flow by equalizing gate and drain potentials and short-circuiting the substrate with the drain or source based on potential differences, ensuring effective protection against overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick gate oxide technology is adopted for high-voltage devices, then the withstandable voltage between gate and substrate is improved, but the transconductance decreases and manufacturing complexity increases
Solution Approach 1:
The patent changes the gate oxide thickness parameter from thick to thin, and introduces a control circuit that dynamically adjusts the gate-substrate voltage to prevent breakdown. This allows using thin gate oxide (which has better transconductance and simpler manufacturing) while maintaining high voltage withstand capability through active control.
2Device complexity
If thin gate oxide technology is adopted for high-voltage devices, then transconductance and manufacturing simplicity are improved, but the withstandable voltage between gate and substrate decreases
Solution Approach 1:
The patent implements a feedback control circuit that continuously monitors the source potential and adjusts the gate potential accordingly. When the source potential is lower than the drain potential, the control circuit ensures the gate potential equals the drain potential, preventing reverse current and gate-substrate breakdown, thus enabling thin gate oxide to be used in high-voltage applications.
3Device complexity
If no reverse current suppression circuit is used, then device simplicity is improved, but the protection against reverse current and overvoltage is insufficient
Solution Approach 1:
The patent implements preliminary protective actions by proactively controlling the gate potential based on the source potential before reverse current or overvoltage damage can occur. The control circuit preemptively adjusts voltages to keep the PMOS transistor in a safe operating state, preventing reverse current flow and gate-substrate breakdown before they can cause damage.
Data Source
AI summary
A reverse current suppression circuit for a PMOS transistor, which includes: a gate drive unit, when the source potential of the first PMOS transistor is lower than the drain potential, the gate drive unit making the gate potential of the first PMOS transistor equal to the drain potential, so that the first PMOS transistor comes into a reverse current suppression state; and a substrate switching unit, when the source potential of the first PMOS transistor is lower than the drain potential, the substrate switching unit short-circuiting the substrate of the first PMOS transistor with the drain of the first PMOS transistor. According to the present invention, when the source potential of the PMOS transistor is lower than the drain potential, the PMOS transistor can be controlled to operate in the reverse current suppression state, so that the PMOS transistor can be effectively protected.