Design and characterization of SOI spiral coil RF monolithic transformers

A 3:4 interwound winding and a 3:4 full symmetrical winding on-chip spiral coil RF monolithic transformers are fabricated using silicon-on-insulator two metal CMOS technology. The major electrical parameters including voltage gain, insertion loss and magnetic coupling coefficient of SOI transformers have been extracted and analyzed. Meanwhile, same transformers based on bulk silicon substrate were also fabricated and compared with those on SOI. The analyses show that SOI transformers have better performances comparing with bulk silicon one and the full symmetrical winding SOI transformer has higher voltage gain, broader bandwidth, less insertion loss than the interwound winding SOI transformer.