Level Shift Circuit Threshold Voltage Optimization
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Solution Overview
Problem
The existing high voltage integrated circuit (HVIC) systems experience delays in signal transmission due to the time required for gate voltage changes in the level shift circuit, which affects the response time of switching elements in power conversion equipment.
Innovation Solution
A semiconductor device with a level shift circuit that transmits input signals from a primary potential system to a secondary potential system, featuring an anterior stage circuit with a first transistor and a posterior stage circuit with a second transistor of the same channel type, where the threshold voltage of the first transistor is set lower than that of the second transistor, reducing the delay time in signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional level shift circuit with high withstand voltage MOSFET is used, then the switching element can be driven in high voltage side, but the delay time in signal transmission increases due to parasitic capacitance
Solution Approach 1:
The patent applies parameter changes by setting different threshold voltages for transistors at different stages of the circuit. Specifically, the first transistor in the anterior stage circuit has a lower threshold voltage than the second transistor in the posterior stage circuit, enabling faster response in the initial signal transmission phase while maintaining proper voltage level shifting throughout the circuit
2Speed
If the threshold voltage of the first transistor is lowered to reduce delay time, then the response time of switching element improves, but the power consumption may increase
Solution Approach 1:
The patent applies local quality by making different parts of the circuit have different threshold voltage characteristics. The first transistor in the anterior stage has a lower threshold voltage optimized for fast response, while the second transistor in the posterior stage has a higher threshold voltage optimized for power efficiency, allowing each part to be optimized for its specific function
Data Source
AI summary
A semiconductor device that has a level shift circuit, an anterior stage circuit, and a posterior stage circuit. The level shift circuit transmits an input signal from a primary potential system to a secondary potential system different from the primary potential system. The anterior stage circuit including a first transistor receives a gate driving signal delivered by the level shift circuit. The posterior stage circuit including a second transistor with the same channel type as that of the first transistor drives a switching element according to the output signal from the first transistor. The threshold voltage of the first transistor is set at a lower value than the threshold voltage of the second transistor.