High-Voltage DC-DC Power Stage Isolation Against Substrate Injection
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Solution Overview
Problem
High-voltage power stages in DC-DC converters face significant substrate injection during switch deadtime, leading to overvoltage stresses and efficiency degradation, as existing technologies fail to adequately address these issues while maintaining circuit efficiency.
Innovation Solution
The implementation of stacked transistors with isolation terminals biased to reduce substrate injection, connected to input DC voltage, boot voltage, Schottky diode, or ground, within high-side and low-side segments of the power stage, utilizing field effect transistors (FETs) to minimize substrate injection effects while preserving circuit efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stacked switch devices are used to form high-voltage power stage, then voltage rating requirement is met, but substrate injection occurs during switch deadtime causing overvoltage stresses and efficiency degradation
Solution Approach 1:
The power stage is divided into multiple stacked switch devices (first and second switch devices) with individual voltage ratings lower than the total power stage voltage. Each switch device handles a portion of the voltage, enabling the system to achieve high-voltage capability while managing substrate injection effects at each individual device level.
Solution Approach 2:
Isolation connections are introduced as intermediary elements between the stacked switch devices and reference potentials (input voltage, ground, or boot voltage). These isolation connections serve as mediators that appropriately bias the substrate of each switch device during deadtime intervals, preventing substrate injection without compromising the voltage rating capability.
2Object-affected harmful factors
If isolation connections are biased to reduce substrate injection, then substrate injection effects are minimized, but circuit operating efficiency may be compromised
Solution Approach 1:
The isolation connections are dynamically configured with multiple possible biasing options (input voltage, ground, or boot voltage) that can be selectively applied based on operational conditions. This dynamic approach allows the system to optimize between substrate injection reduction and circuit efficiency by choosing the most appropriate isolation connection configuration for each operating state.
Solution Approach 2:
The biasing parameter of the isolation connections is changed based on operational requirements. By adjusting which reference potential (input voltage, ground, or boot voltage) is applied to each isolation connection, the system can modify the electrical parameters to minimize substrate injection effects while maintaining optimal circuit efficiency during different operating phases.
3Object-affected harmful factors
If isolation connections are configured to reduce substrate injection, then overvoltage stresses are prevented, but device complexity increases
Solution Approach 1:
The isolation connections serve multiple functions: they provide substrate biasing to prevent substrate injection, protect against overvoltage stresses, and maintain circuit efficiency. By designing the isolation connection system to handle multiple protective and operational functions simultaneously, the patent reduces overall device complexity compared to having separate circuits for each function.
Data Source
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AI summary
Embodiments of a power stage for a direct current (DC)-DC converter and a DC-DC converter are disclosed. In an embodiment, a power stage for a DC-DC converter includes an input terminal from which input power of the DC-DC converter with an input DC voltage is received, a high-side segment connected between the input DC voltage and an output signal of the power stage, and a low-side segment connected between the output signal of the power stage and ground. At least one of the high-side segment and the low-side segment includes stacked transistors having isolation terminals that are biased to reduce substrate injection.