Half-Bridge Semiconductor Layout for Balanced Wire Inductance
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Solution Overview
Problem
In semiconductor devices, the imbalance in inductance between the upper and lower arm switching devices and diode devices leads to either a decrease in switching speed or an increase in free-wheeling current, causing deterioration and inefficiency in half-bridge circuits.
Innovation Solution
The semiconductor device design includes a configuration where the inductances of the wires coupling the switching devices and diode devices are made substantially equal, with the semiconductor chips arranged in specific patterns to minimize manufacturing variations, thereby balancing the inductance and reducing free-wheeling current while maintaining switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inductance on the source side of the MOSFET is increased to suppress free-wheeling current through the body diode, then the current flowing through the body diode is reduced, but the voltage drop due to inductance lowers the gate-source voltage and decreases switching speed
Solution Approach 1:
The patent applies asymmetry by intentionally creating different inductance values in different circuit paths. Specifically, the source-side inductance of the MOSFET is made larger than the anode-side inductance of the Schottky barrier diode, creating an asymmetric inductance distribution that directs free-wheeling current preferentially through the Schottky barrier diode rather than the MOSFET body diode, thereby protecting the MOSFET while managing the voltage drop effect
2Speed
If the inductance on the source side of the MOSFET is decreased to maintain switching speed, then the voltage drop due to inductance is reduced, but the current flowing through the body diode increases and accelerates MOSFET deterioration
Solution Approach 1:
The patent introduces the Schottky barrier diode as an intermediary element in the free-wheeling current path. By placing this diode with controlled anode-side inductance between the MOSFET and the load, it serves as a mediator that absorbs part of the free-wheeling current, reducing the burden on the MOSFET body diode and allowing the source-side inductance to be optimized for switching speed without excessive MOSFET stress
3Reliability
If wire lengths are made substantially equal to balance inductance, then inductance differences are minimized and free-wheeling current is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by deliberately designing specific inductance values for different wire paths rather than making all wires identical. The source-side wire connecting to the MOSFET is designed with larger inductance parameters, while the anode-side wire to the Schottky barrier diode has smaller inductance parameters. This controlled parameter differentiation achieves optimal current distribution and MOSFET protection while being compatible with standard manufacturing tolerances
Data Source
AI summary
A semiconductor device, including first and second conductive patterns, a plurality of first semiconductor chips each having a switching device, a plurality of second semiconductor chips each having a diode device, a plurality of first wires, respectively coupling low-potential electrodes of the switching devices and the second conductive pattern, and a plurality of second wires, respectively coupling anode electrodes of the diode devices and the second conductive pattern. Lengths of the first and second wires are substantially equal. The first semiconductor chips and the second semiconductor chips are arranged on the first conductive pattern in two rows, each row being in a first direction and including at least one first semiconductor chip and at least one second semiconductor chip, the first direction being parallel to a predetermined side of the first conductive pattern. The first and second wires are each in a second direction orthogonal to the first direction.