Key Takeaways & Executive Findings
- •• Fully integrated isolated power converters with on-chip transformers are favored for compactness and >5 kV isolation, but early designs suffer from low efficiency (<34%) due to low Q-factor of on-chip transformers. • Specialized fabrication techniques, such as laminated magnetic cores and ultra-thick metal windings, improve transformer Q-factor and efficiency, achieving up to 52% peak efficiency. • Transformer-in-package designs offer a balance between integration and performance, addressing limitations of silicon-based windings. • Key challenges include multi-stage power conversion efficiency losses and EMI compliance with standards like CISPR-32 and EN-55032 Class B.
Abstract
Isolated power converters have emerged as an active research topic in power integrated circuit (IC) design. Reflecting this growing interest, ISSCC 2025 has featured a dedicated session on "Isolated Power and Gate Drivers". These converters enable safe and reliable power delivery across voltage domains and are widely used in renewable energy, electric vehicles, and telecommunications. Galvanic isolation prevents surge currents and ground loop issues in harsh high-voltage environments. As demand grows for compact, efficient, and high–power-density solutions, fully integrated architectures featuring on-chip transformers are increasingly favored over traditional module-based designs, offering >5 kV isolation with a smaller footprint and lower system cost. This mini review highlights recent advances and trends in isolated power converter technologies, focusing on efficiency improvement and EMI suppression.
1. Introduction
Isolated power converters have emerged as an active research topic in power integrated circuit (IC) design. Reflecting this growing interest, ISSCC 2025 has featured a dedicated session on "Isolated Power and Gate Drivers". These converters enable safe and reliable power delivery across voltage domains and are widely used in renewable energy, electric vehicles, and telecommunications. Galvanic isolation prevents surge currents and ground loop issues in harsh high-voltage environments.
As demand grows for compact, efficient, and high–power-density solutions, fully integrated architectures featuring on-chip transformers are increasingly favored over traditional module-based designs, offering >5 kV isolation with a smaller footprint and lower system cost. As illustrated in Fig. 1, an isolated converter typically consists of a transmitter (TX), a transformer, and a receiver (RX). The TX performs DC–AC conversion using an inverter, the RX performs AC–DC conversion through a rectifier, and output voltage regulation is achieved via feedback control, often implemented through a digital isolator. The first major challenge is that multi-stage power conversion reduces overall efficiency, primarily due to transformer and rectifier limitations. The second is that switching large currents at high frequencies generates significant EMI, making it difficult to comply with standards such as CISPR-32 and EN-55032 Class B. This mini review highlights recent advances and trends in isolated power converter technologies, focusing on efficiency improvement and EMI suppression.
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Lin Cheng, Dongfang Pan (2025). Trends and emerging techniques in isolated power converters. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/25040037
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Frequently Asked Questions
What are isolated power converters and why are they important?
Isolated power converters provide galvanic isolation between input and output, ensuring safe and reliable power delivery across voltage domains. They are crucial in applications like renewable energy, electric vehicles, and telecommunications, where they prevent surge currents and ground loop issues in harsh high-voltage environments.
What are the main challenges in isolated power converter design?
The main challenges include low efficiency due to multi-stage power conversion and transformer/rectifier losses, and significant electromagnetic interference (EMI) from high-frequency switching, which must comply with standards like CISPR-32 and EN-55032 Class B.
How can efficiency be improved in isolated power converters?
Efficiency can be improved by enhancing transformer performance through specialized fabrication techniques, such as using laminated magnetic cores or ultra-thick metal windings to increase the Q-factor and coupling coefficient, thereby reducing losses.
What are the advantages of fully integrated isolated power converters?
Fully integrated architectures with on-chip transformers offer compact size, lower system cost, and >5 kV isolation, making them attractive for high-power-density applications compared to traditional module-based designs.
What is the role of transformer-in-package designs?
Transformer-in-package designs balance integration and performance by alleviating the thickness and width limitations of silicon-based windings, potentially achieving better efficiency while maintaining a relatively compact footprint.
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