An X-Band Transformer-Coupled Varactor-Less Quadrature Current-Controlled Oscillator in 0.18 $\mu{\hbox {m}}$ SiGe BiCMOS Technology

This paper presents a transformer-coupled varactor- less quadrature current-controlled oscillator (QCCO) RFIC covering the entire X-Band from 8.7 GHz to 13.8 GHz. The QCCO incorporates a transformer-coupled technique that achieves frequency tuning by varying the bias currents in the primary and secondary windings. Fabricated in a 0.18 μm SiGe BiCMOS technology, the prototype QCCO achieves a 45.3% wide tuning range. With two stacked octagonal transformers the QCCO core circuit occupies 0.4 × 0.5 mm² chip area and draws 8-18 mA current under a 1.8 V power supply. The measured phase noise for 11.02 GHz quadrature outputs is about - 110 dBc/Hz at 10MHz offset. The QCCO achieves a phase noise, power and area efficiency figure-of-merit of -191 dBc/Hz.