Gate Leakage Monitoring via Capacitor Voltage in Power Switches

The patent introduces a capacitor as an intermediary element between the gate resistor and ground. This capacitor converts the difficult-to-measure leakage current into an easily detectable voltage signal through charge accumulation (Q=CV), where the voltage across the capacitor directly reflects the integrated leakage current. This intermediary approach solves the measurement precision problem while keeping the overall circuit structure relatively simple.

The patent replaces direct current measurement (electrical measurement) with voltage measurement through capacitive coupling. Instead of measuring the noisy leakage current directly through the gate resistor, the system measures the voltage developed across the capacitor, which is a cleaner signal that can be detected with higher precision using standard voltage sensing circuits.

The patent implements preliminary monitoring of gate leakage current before the gate oxide layer fails completely. By continuously detecting leakage current and issuing warnings when thresholds are exceeded, the system can take preventive actions (such as reducing power or shutting down) before catastrophic failure occurs, thus compensating for the reduced inherent reliability of thinner oxide layers.

The patent establishes a feedback mechanism where the detected gate leakage current is continuously monitored and compared against predefined thresholds. When the leakage current exceeds the threshold, a warning signal is generated to alert the control system. This feedback loop enables real-time assessment of gate oxide health, allowing the system to adapt its operation to maintain reliability despite using thinner oxide layers for higher productivity.

The patent merges the gate leakage current monitoring function with the existing gate driver circuitry. The capacitor is connected to the gate driver output, and the monitoring is performed using the same control logic that drives the power switch. This integration approach enables safety monitoring without adding completely separate monitoring circuits, thus improving reliability while minimizing the increase in device complexity.

The monitoring apparatus is designed to serve multiple functions: it monitors gate leakage current for safety, provides early warning of degradation, and can trigger protective actions. The same circuit components (capacitor, voltage divider, comparator) are used to achieve both the monitoring and the protective control functions, making the system multi-functional and reducing overall complexity.