Monolithic Transformers for High Frequency Bulk CMOS Circuits

This paper presents two monolithic transformer structures exhibiting high self resonance frequencies(fSR). Effect of positive and negative coupling factor on self resonance frequency is investigated. The transformer turn ratio and structure is selected to improve design and ease layout of a high frequency LNA and VCO. Measurement results of a transformer show good agreement with simulated values and demonstrate a coupling factor of 0.7 at 20 GHz.