This paper proposes a 3.2-GHz quadrature signal generator, which consists of a single-stage LC voltage-controlled oscillator (VCO) and a phase separator. The LC VCO consists of a PMOS cross-coupled pair and a parallel LC resonant circuit to achieve low phase noise. The phase separator consists of a three-stage RC quadrature network to mitigate the effect of process variation. The measured frequency of the free-running VCO is 3.19 GHz. The measured phase noise values 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. The current consumption of the quadrature signal generator is 9 mA at a 2.5-V DC voltage. The quadrature signal generator is implemented in the TSMC 0.25-μm CMOS process with a total chip size of 0.98 × 0.99 mm2.
Advances in Mathematical and Computational Methods, 1(1), 28-33