Ultra-High-Isolation Mutual-Embedded Transformer in Organic Substrate for Digital Isolator

In this letter, an ultra-high-isolation mutual-embedded transformer in organic substrate (METOS) of digital isolators is proposed and demonstrated for ultra-high isolation and excellent transmission performances simultaneously. At the micro-electromechanical system (MEMS) scale, the METOS adopts coupling coils completely embedding in isolation material for the first time. With an area of 1.16 mm2, the METOS, fabricated on a 1-mm silicon wafer using MEMS processes, has
$100~\mu \text{m}$
thick isolation layers between each turn of the primary and secondary coils. The METOS has achieved an excellent transformer efficiency over a wide band of 80–720 MHz, and its transformer efficiency is 89.55% at 374 MHz. The METOS isolation capability of more than 7.5 kV has also been measured. The ultra-high isolation and excellent transmission performances of the METOS, are very promising for efficient high-voltage isolated signal transfer applications.