CSTBT Simulation Circuit With Behavioral VDG Switching
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Solution Overview
Problem
Existing simulation methods for Carrier Stored Trench Bipolar Transistors (CSTBT) do not accurately reflect the operation of the carrier storage layer, leading to inaccuracies in simulating the electrical characteristics of CSTBT devices.
Innovation Solution
A simulation model for CSTBT that includes a MOSFET, diode, and various capacitances (CGE, CCG, CCE, CDG) with a behavioral power source VDG, accurately simulating the CSTBT's behavior by representing gate-emitter, gate-collector, collector-emitter, and drain-gate capacitances, and the switching operation of VDG based on a threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional SPICE model is used for simulating CSTBT, then the simulation can be performed with standard tools, but the simulation accuracy is insufficient because the carrier storage layer behavior is not reflected
Solution Approach 1:
The CSTBT is segmented into distinct functional components: a MOSFET representing the channel region and a separate diode representing the carrier storage layer. This segmentation allows each component to be modeled independently with appropriate physical characteristics, enabling accurate representation of the carrier storage effect without requiring a complete physical model of the entire device structure.
Solution Approach 2:
A behavioral power supply VDG is introduced as an intermediary element connected between the drain and gate. This behavioral source dynamically adjusts the drain-gate voltage based on the gate-emitter voltage threshold, effectively mediating the interaction between the MOSFET and diode to reproduce the characteristic sharp increase in gate-emitter voltage and subsequent current flow that defines CSTBT operation.
2Measurement precision
If physical parameter extraction methods are used to achieve accurate simulation, then simulation precision improves, but the requirement for semiconductor physics knowledge increases making it difficult for general circuit designers
Solution Approach 1:
Instead of requiring circuit designers to extract and input complex physical parameters from semiconductor physics models, the invention creates a behavioral copy of the CSTBT's electrical characteristics using standard circuit elements. The model reproduces the essential I-V characteristics and switching behavior through the interaction of the MOSFET, diode, and behavioral power supply, eliminating the need for physicists-level parameter extraction while maintaining simulation accuracy.
Solution Approach 2:
The model transitions from using fixed physical parameters requiring expert extraction to using behavioral parameters that can be directly observed from device operation. The behavioral power supply VDG changes its output based on the threshold condition of gate-emitter voltage, dynamically adjusting the drain-gate voltage to match real device behavior without requiring explicit physical parameter specification by the user.
3Reliability
If the carrier storage layer is not included in the model, then the model simplicity is maintained, but the operation of CSTBT cannot be accurately expressed
Solution Approach 1:
The carrier storage layer functionality is extracted from the complex physical structure and represented by a separate diode component connected to the MOSFET. This extracted representation captures the essential charge storage and release behavior without requiring the full physical complexity of the carrier storage layer, enabling accurate operational representation with reduced model complexity.
Data Source
AI summary
An object of the present disclosure is to accurately simulate the operation of a CSTBT. The simulation model of a CSTBT includes a MOSFET, a diode whose cathode is connected to the drain of the MOSFET, capacitance CGE connected between a source and a gate of the MOSFET, capacitance CCG connected between a gate of the MOSFET and an anode of the diode, capacitance CCE connected between a source of the MOSFET and the anode of the diode, capacitance CDG connected between the drain and the gate of the MOSFET, and a behavioral power source VDG connected in series to the capacitance CDG between the drain and the gate of the MOSFET. The behavioral power source VDG performs a switching operation when gate-emitter voltage VGE of the CSTBT reaches a predetermined threshold value.