Gate Drive Circuit for In-Situ Semiconductor Gate Resistance Sensing
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Solution Overview
Problem
Existing methods for detecting gate resistance in semiconductor switching elements with high breakdown voltage are cumbersome, require additional circuitry, and increase circuit area, often necessitating high-resolution ADCs and prior measurement of parasitic inductance or capacitor values.
Innovation Solution
An electronic circuit that selectively performs driving and measurement operations using shared transistors, inputting a pulse current during off periods to sample gate voltage at different times, allowing calculation of gate resistance without direct ADC conversion and reducing circuit area by sharing transistors for both functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sine wave current is input to detect gate voltage, then gate resistance can be detected, but gate parasitic inductance must be measured in advance and circuit area increases
Solution Approach 1:
The transistor is designed to perform dual functions: driving the semiconductor switching element and measuring gate resistance. By using the same transistor for both operations, the need for separate measurement circuits is eliminated, reducing circuit area while maintaining measurement capability
Solution Approach 2:
Gate resistance measurement is performed during the off period before the next driving operation begins. This preliminary measurement during idle time avoids interfering with normal operation and eliminates the need for separate measurement circuits
2Measurement precision
If gate voltage is directly AD-converted to calculate gate resistance, then calculation accuracy improves, but high-resolution ADC is required increasing circuit complexity
Solution Approach 1:
Instead of directly converting gate voltage, the invention changes the measurement parameter by measuring current through the transistor during off period. This indirect measurement method achieves accurate gate resistance calculation without requiring high-resolution ADC, as the current measurement can be performed with simpler circuitry
Solution Approach 2:
The transistor itself serves as an intermediary element for measurement. By measuring the current flowing through the transistor during off period, the gate resistance is indirectly obtained without directly converting gate voltage, avoiding the need for high-resolution ADC
3Measurement precision
If additional circuit for current input is added, then gate resistance measurement is enabled, but circuit area increases
Solution Approach 1:
The transistor is designed to perform dual functions: driving the semiconductor switching element and measuring gate resistance. By using the same transistor for both operations, the need for separate measurement circuits is eliminated, reducing circuit area while maintaining measurement capability
Solution Approach 2:
The transistor serves itself for measurement purposes. During off period, the transistor naturally allows current flow that can be measured to determine gate resistance, eliminating the need for external current input circuits
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
Enables accurate detection of gate resistance and temperature estimation without the need for high-resolution ADCs or additional circuit paths, reducing circuit complexity and area while allowing continuous operation of the semiconductor switching element.
Implementation Method 1
a gate voltage having a trapezoid wave is measured at two points of time, such a gate voltage being generated due to the parasitic capacitor and the parasitic resistance
Implementation Method 2
The voltage across the gate resistance is amplified to convert the amplified voltage into a DC (Direct Current) voltage by a detection circuit
Data Source
AI summary
According to one embodiment, an electronic circuit includes a plurality of first transistors, a control circuit, a sample hold circuit and a calculation circuit. The control circuit selectively performs a first operation and a second operation, the first operation supplying a driving control signal to a gate terminal of a semiconductor switching element using the plurality of first transistors, and the second operation supplying a pulse current for measurement to the gate terminal using part of the plurality of first transistors. The sample hold circuit samples a voltage of the gate terminal during a period in which the pulse current is supplied to the gate terminal in the second operation. The calculation circuit calculates a gate resistance of the semiconductor switching element based on the sampled voltage.