Semiconductor Switching Circuit for Drain Voltage Slope Control
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Solution Overview
Problem
Semiconductor integrated circuits with normally-on and normally-off type switching elements face challenges in suppressing steep shifts in drain voltage of the normally-on type switching element when the normally-off type switching element is turned on/off, leading to unnecessary radiation.
Innovation Solution
Incorporating a resistor and capacitors in specific configurations between the gate and source of the normally-on type switching element, allowing for adjustment of the gate-source voltage by capacitance values and resistance, thereby controlling the on-state of the normally-on type switching element to mitigate steep voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a normally-on type switching element is used to provide high voltage resistance and low loss, then the voltage resistance and loss characteristics are improved, but the drain voltage shifts steeply when the normally-off type switching element is turned on, generating unnecessary radiation
Solution Approach 1:
The capacitor is charged in advance during the period when the normally-off switching element is off, storing energy. When the normally-off switching element is turned on, the capacitor discharges to supply current and suppress the steep voltage shift, preventing radiation generation while maintaining the low-loss characteristics of the normally-on switching element
Solution Approach 2:
The capacitor acts as an intermediary energy storage device between the power supply and the normally-on switching element. It mediates the voltage transition by providing additional current during switching, thereby suppressing the steep drain voltage shift and the resulting radiation without affecting the normal operation of the switching elements
2Reliability
If a normally-on type switching element is used, then high voltage resistance is achieved, but the gate-source voltage must be precisely controlled to prevent instantaneous turn-on and steep drain voltage shifts
Solution Approach 1:
The capacitor is pre-charged during the off-period of the normally-off switching element, preparing the necessary energy in advance. This preliminary energy storage simplifies the control requirements by ensuring that current is available to suppress voltage shifts without requiring complex real-time control mechanisms
Solution Approach 2:
The control signal that turns off the normally-off switching element is also used to trigger the charging of the capacitor. This feedback mechanism ensures that the capacitor is always charged and ready to suppress voltage shifts when the normally-off element is turned on, maintaining reliable voltage resistance with simplified control logic
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
This configuration effectively adjusts the gate voltage of the normally-on type switching element, reducing steep drain voltage changes and minimizing unnecessary radiation during switching operations.
Implementation Method 1
a first capacitor that is connected in parallel to the resistor, and a second capacitor between the gate and the source of the first switching element
Data Source
AI summary
According to one embodiment, a semiconductor integrated circuit includes a normally-on type first switching element that has a source, a drain, and a gate, a normally-off type second switching element that has a drain that is connected to the source of the first switching element, a gate that is supplied with a driving signal, and a source, a resistor that is connected between the gate of the first switching element and the source of the second switching element, a first capacitor that is connected in parallel to the resistor, and a second capacitor between the gate and the source of the first switching element.