Thin film microtransformer integrated on silicon for signal isolation

Microtransformers have been fabricated on silicon substrates with the aim of providing isolation for signal and power. Interleaved primary and secondary windings are sandwiched between two electroplated magnetic layers. The transformer has a turn ratio of 4:4. It has a primary inductance of 400 nH at low frequencies and dc resistance of 0.48 Ω. The voltage gain is -1 dB between 1-20 MHz with a 50-Ω load. When compared to previously reported microtransformer characteristics this is the highest reported voltage gain for a microtransformer.