5 GHz CMOS Quadrature VCO Using Trifilar-Transformer-Coupling Technology

A trifilar-transformer-coupling quadrature voltage-controlled oscillator (TTC-QVCO) with dual transformer-feedback technology is proposed. Compared to traditional QVCOs, the proposed TTC-QVCO provides an additional coupling path, and therefore achieves an improved quadrature phase accuracy, a lower phase noise and a wider tuning range. The TTC-QVCO, implemented in a 0.18-μm CMOS technology, exhibits a frequency tuning range of 19.6% centered at 5.4 GHz and a power consumption of 5.4 mW from a 1.35 V supply voltage. The QVCO has a measured phase noise of -120.42 dBc/Hz at 1-MHz offset and quadrature phase error of less than 2° with a FoMT of 194.3 dB.