An LC Quadrature VCO With Compensated Coupling Networks for Low Supply Sensitivity and I/Q Phase Enhancement

An LC quadrature voltage-controlled oscillator (LC-QVCO) with novel compensated coupling networks to achieve both low supply sensitivity and quadrature phase enhancement is proposed. Designed and fabricated in a standard 0.18-μm CMOS process, the proposed QVCO improves the supply noise rejection by more than 16.72 dB compared with the conventional LC-QVCO and achieves quadrature phase error of < 0.86° within the frequency tuning range from 3.32 to 3.52 GHz, whereas occupying a core area of 504 × 400 μm² and consuming 3.2 mA including the bias circuitry, from a 1.8-V supply voltage. The phase noise is measured to be −110.64 dBc/Hz at 1 MHz offset and −130.49 dBc/Hz at 10 MHz offset from the high-band carrier frequency at 3.52 GHz.