A FoM of −191 dB, 4.4-GHz LC-VCO Integrating an 8-Shaped Inductor with an Orthogonal-Coupled Tail-Filtering Inductor

A 4.25–4.65 GHz LC-VCO with tailing filter technique integrating an 8-shaped inductor with an orthogonal-coupled tail-filtering inductor is presented in this paper. The mutual inductance between the 8-shaped inductor and the tail-filtering inductor is negligible due to the symmetrical and reversal magnetic field by the two loops of the 8-shaped inductor, which avoids the additional chip area occupation of the bulky tail-filtering inductor. The VCO is implemented in TSMC 180 nm CMOS process, obtaining a tuning range (TR) of 0.4 GHz, which consumes 7.7 mA current from a 1 V power supply. By adopting the 8-shaped inductor and noise filtering technique from the orthogonal-coupled inductor, the post-layout simulated phase noise achieves –126.7 dBc/Hz at 1 MHz offset away from the 4.4 GHz carrier and the resulting figure-of-merit (FoM) is −191 dB.