A 3.2-GHz Quadrature Signal Generator Based on a Single-Stage LC VCO in 0.25-μm CMOS Process

This paper proposes a 3.2-GHz quadrature signal generator, which consists of asingle-stage LC voltage-controlled oscillator (VCO) and a phase separator. The LC VCO consists ofa PMOS cross-coupled pair and a parallel LC resonant circuit to achieve low phase noise. Thephase separator consists of a three-stage RC quadrature network to mitigate the effect of processvariation. The measured frequency of the free-running VCO is 3.19 GHz. The measured phase noisevalues from oscillator signals of 100-kHz and 1-MHz offset frequencies are -106.6 and -116 dBc/Hz,respectively. The measured frequency from the quadrature generator output is 3.18 GHz. Thecurrent consumption of the quadrature signal generator is 9 mA at a 2.5-V DC voltage. Thequadrature signal generator is implemented in the TSMC 0.25-μm CMOS process with a total chipsize of 0.98 × 0.99 mm2.