Voltage Tracking Circuit for NMOS Over-Voltage Leakage Control
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Solution Overview
Problem
In electronic circuits using N-type metal oxide semiconductor (NMOS) transistors, over-voltage events can cause the parasitic bipolar diode to turn on, leading to leakage currents that result in overheating and damage to the circuit, necessitating a solution to reduce such currents.
Innovation Solution
A voltage tracking circuit comprising P-type transistors and a control circuit that compares voltages at different terminals to generate an output voltage, applying it to an isolated deep well region surrounding a high-voltage-side element, thereby controlling the parasitic bipolar transistor and reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If an NMOS transistor is used on the high-voltage side, then the circuit can handle high voltage, but leakage current increases due to parasitic bipolar diode turn-on during over-voltage events
Solution Approach 1:
The patent introduces a voltage tracking circuit as an intermediary between the high-voltage side and the deep well region. This circuit includes P-type transistors (first and second P-type transistors) that track the voltage difference between the high-voltage side and ground, generating a control voltage that is applied to the deep well region to suppress parasitic bipolar diode turn-on and reduce leakage current
2Object-generated harmful factors
If a voltage tracking circuit is introduced to reduce leakage current, then leakage current is reduced, but power consumption increases
Solution Approach 1:
The voltage tracking circuit dynamically adjusts the control voltage applied to the deep well region based on the real-time voltage difference between the high-voltage side and ground. The P-type transistors continuously track this voltage difference and adjust their conduction state accordingly, ensuring the deep well region receives appropriate bias voltage only when needed to suppress leakage current, rather than maintaining a fixed high bias voltage that would consume excessive power
Solution Approach 2:
The circuit changes the voltage parameter applied to the deep well region dynamically based on operating conditions. The control voltage is adjusted according to the voltage tracking result, transitioning between different voltage states to suppress leakage current during over-voltage events while reducing power consumption during normal operation
Data Source
AI summary
A voltage tracking circuit is provided. The voltage tracking circuit includes first and second P-type transistors and a control circuit. The drain of the first P-type transistor is coupled to a first voltage terminal. The gate and the drain of the second P-type transistor are respectively coupled to the first voltage terminal and a second voltage terminal. The control circuit is coupled to the first and second voltage terminals and generates a control voltage according to the first voltage and the second voltage. The sources of the first and second P-type transistors are coupled to an output terminal of the voltage tracking circuit, and the output voltage is generated at the output terminal. In response to the second voltage being higher than the first voltage, the control circuit generates the control signal to turn off the first P-type transistor.