SiGe HBT quadrature VCO utilizing trifilar transformers

A trifilar-coupling quadrature voltage-controlled oscillator (QVCO) is demonstrated using 0.35-mum SiGe heterojunction bipolar transistor (HBT) technology. The trifilar transformer consisting of one primary coil and two secondary coils is used in this work to separate the collector and base bias for output voltage swing optimization and also to replace a conventional transistor-coupling method for quadrature output generation, simultaneously. As a result, the trifilar-coupling QVCO achieves the 191.6-dBc/Hz FOM at the supply voltage of 1.2 V The on-chip passive single side-band (SSB) upconversion mixer is also demonstrated to fairly measure the quadrature accuracy of the QVCO. Consequently, the side-band rejection ratio of 37.7 dB is achieved.